1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
#include <cstdio>
#include <cstring>
#include <string>
#include <algorithm>
#include <vector>
#include <stack>
#include <queue>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <cstdlib>
#include <cassert>
#include <cmath>
#include <cstdarg>
using namespace std;
#define ALL(x) (x).begin(), (x).end()
#ifdef DBG
#define DBGprint(format, ...) do { fprintf(stderr, "[%s:%d] " format "\n", __func__, __LINE__, ## __VA_ARGS__); } while (0)
#else
#define DBGprint(...) do { } while (0)
#endif

typedef long double LD;
typedef double DL;
typedef long long LL;
typedef unsigned long long ULL;
typedef pair<LD,LD> PLD;
typedef pair<int,int> PII;
typedef pair<LL,LL> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<PII> VPII;
void memcheck()
{
#ifdef DBG
    char c[100];
    FILE *p = fopen("/proc/self/status","r");
    while (fgets(c,100,p) )
        if (strncmp("VmPeak",c,6)==0)
            fputs(c, stderr);
    fclose(p);
#endif
}
//------ /headers --------

struct Tribe {
    int x1, x2, y1, y2;
    Tribe() = default;
    Tribe(int x1, int x2, int y1, int y2) :
            x1(x1), x2(x2), y1(y1), y2(y2) { }
    tuple<int, int, int, int> tuplify() const {
        return tuple<int, int, int, int>(x1, x2, y1, y2);
    }
};
int tribes_cnt;
vector<Tribe> tribes;

bool intersect(const Tribe& t1, const Tribe& t2) {
    return t1.x1 < t2.x2 && t1.x2 > t2.x1 && t1.y1 < t2.y2 && t1.y2 > t2.y1;
}

bool intersect(int t1_no, int t2_no) {
    return intersect(tribes[t1_no], tribes[t2_no]);
}

struct CompareTribes {
    bool operator () (int a, int b) {
        if (tribes[a].x2 == tribes[b].x2) {
            return a < b;
        }
        return tribes[a].x2 < tribes[b].x2;
    }
};

struct Node {
    // trzymamy numery plemion, posortowane po x2
    set<int, CompareTribes> past;
    // to sa te, ktore powstaly przez pojscie w gore drzewa
    set<int, CompareTribes> past_up;
};

set<int> monitored{1434, 1371};

struct Tree {
    // do 10^6
    static const int OFFSET = (1 << 20);
    static const int SIZE = 2 * OFFSET;

    vector<Node> nodes;
    // w ktorych wezlach siedzi dane plemie
    vector<VI> tribes_pos_past;
    vector<VI> tribes_pos_past_up;

    Tree() : nodes(SIZE), tribes_pos_past(SIZE), tribes_pos_past_up(SIZE) {}

    // zwraca numer plemiona, ktore przecina lub -1
    int insert_node(int pos, int tribe_no) {
        // jest cos ciekawego?
        if (!nodes[pos].past.empty()) {
            auto it = nodes[pos].past.end();
            // idziemy 2 (ostatni mozemy byc my)
            for (int i = 0; i < 2; ++i) {
                --it;
                int last = *it;
                if (last != tribe_no && intersect(last, tribe_no)) {
                    // weee!!!
                    return last;
                }
            }
        }
        nodes[pos].past.insert(tribe_no);
        tribes_pos_past[tribe_no].push_back(pos);
#ifdef DBG
        DBGprint(" nodes[%d].past_up: ", pos);
        fprintf(stderr, "   ");
        for (int i : nodes[pos].past) {
            fprintf(stderr, " %d", i);
        }
        fprintf(stderr, "\n");
#endif
        // idziemy do hory
        while (pos > 0) {
            // jest cos ciekawego?
            if (!nodes[pos].past_up.empty()) {
                auto it = nodes[pos].past_up.end();
                // idziemy 2 (ostatni mozemy byc my)
                for (int i = 0; i < 2; ++i) {
                    --it;
                    int last = *it;
                    if (last != tribe_no && intersect(last, tribe_no)) {
                        // weee!!!
                        return last;
                    }
                }
            }
            if (!nodes[pos].past.empty()) {
                auto it = nodes[pos].past.end();
                // idziemy 2 (ostatni mozemy byc my)
                for (int i = 0; i < 2; ++i) {
                    --it;
                    int last = *it;
                    if (last != tribe_no && intersect(last, tribe_no)) {
                        // weee!!!
                        return last;
                    }
                }
            }
            auto it = nodes[pos].past_up.find(tribe_no);
            if (it == nodes[pos].past_up.end()) {
                nodes[pos].past_up.insert(tribe_no);
                tribes_pos_past_up[tribe_no].push_back(pos);
            }
            DBGprint(" nodes[%d].past_up: ", pos);
#ifdef DBG
            fprintf(stderr, "   ");
            for (int i : nodes[pos].past_up) {
                fprintf(stderr, " %d", i);
            }
            fprintf(stderr, "\n");
#endif
            pos /= 2;
        }
        return -1;
    }

    // zwraca numer plemiona, ktore przecina lub -1
    int insert_aux(int tribe_no, int from, int to, int pos, int left, int right) {
//         DBGprint("          insert tribe %d [%d-%d]   {%d %d-%d}", tribe_no, from, to, pos, left, right);
        if (from == left && to == right) {
            DBGprint("insert tribe %d [%d-%d]   {%d %d-%d}", tribe_no, from, to, pos, left, right);
            int k = insert_node(pos, tribe_no);
//             DBGprint("insert tribe %d [%d-%d]   {%d %d-%d} ---> %d", tribe_no, from, to, pos, left, right, k);
            return k;
        }
        if (left >= right - 1) {
            return -1;
        }
        int m = (left + right) / 2;
        int ret_left = -1, ret_right = -1;
        if (from < m) {
            ret_left = insert_aux(tribe_no, from, min(m, to), pos * 2, left, m);
        }
        if (to > m) {
            ret_right = insert_aux(tribe_no, max(from, m), to, pos * 2 + 1, m, right);
        }
//         if (ret_left != -1) {
//             DBGprint("found left tribe %d {%d %d-%d}", ret_left, pos, left, right);
//         }
//         if (ret_right != -1) {
//             DBGprint("found right tribe %d {%d %d-%d}", ret_right, pos, left, right);
//         }
        return ret_left != -1 ? ret_left : ret_right;
    }

    void connect_tribes(int tribe, int incorpd) {
        tribes[tribe].x1 = min(tribes[tribe].x1, tribes[incorpd].x1);
        tribes[tribe].y1 = min(tribes[tribe].y1, tribes[incorpd].y1);
        tribes[tribe].x2 = max(tribes[tribe].x2, tribes[incorpd].x2);
        tribes[tribe].y2 = max(tribes[tribe].y2, tribes[incorpd].y2);
        tribes[incorpd].x1 = tribes[incorpd].x2 = tribes[incorpd].y1 = tribes[incorpd].y2 = -1;
    }

    void erase(int tribe_no) {
        for (int pos : tribes_pos_past[tribe_no]) {
            nodes[pos].past.erase(tribe_no);
        }
        for (int pos : tribes_pos_past_up[tribe_no]) {
            nodes[pos].past_up.erase(tribe_no);
        }
        tribes_pos_past[tribe_no].clear();
        tribes_pos_past_up[tribe_no].clear();
    }

    // usuwa lub wstawia, przy czym poki jest przeciecie, usuwa je
    void insert(int tribe_no) {
        // wstawiamy
        DBGprint("insert %d : [%d-%d] [%d-%d]",
                tribe_no, tribes[tribe_no].x1, tribes[tribe_no].x2,
                tribes[tribe_no].y1, tribes[tribe_no].y2);
        int k = insert_aux(tribe_no, tribes[tribe_no].y1, tribes[tribe_no].y2, 1, 0, OFFSET);
        if (k != -1) {
            DBGprint("  join %d [%d-%d] [%d-%d]  <>  %d [%d-%d] [%d-%d]",
                    k, tribes[k].x1, tribes[k].x2, tribes[k].y1, tribes[k].y2,
                    tribe_no, tribes[tribe_no].x1, tribes[tribe_no].x2, tribes[tribe_no].y1, tribes[tribe_no].y2);
            // usuwamy oba
            erase(tribe_no);
            erase(k);
            // laczymy
            connect_tribes(tribe_no, k);
            // wstawiamy nowe
            insert(tribe_no);
        }
    }
};

Tree tree;

void sweep() {
//     for (const Event& event : events) {
//         tree.insert(event.tribe);
//     }
    for (int i = 0; i < tribes.size(); ++i) {
        tree.insert(i);
#ifdef DBG
        for (int j = 0; j <= i; ++j) {
            if (tribes[j].x1 != -1) {
                DBGprint("rects[%d] [%d-%d] [%d-%d]", j, tribes[j].x1, tribes[j].x2, tribes[j].y1, tribes[j].y2);
            }
            if (i < j && intersect(i, j)) {
                DBGprint("ERROR: %d ([%d-%d] [%d-%d]) %d ([%d-%d] [%d-%d])",
                         i, tribes[i].x1, tribes[i].x2, tribes[i].y1, tribes[i].y2,
                         j, tribes[j].x1, tribes[j].x2, tribes[j].y1, tribes[j].y2);
            }
        }
#endif
    }
}

int main() {
    scanf("%d", &tribes_cnt);
    for (int i = 0; i < tribes_cnt; ++i) {
        int a, b, c, d;
        scanf("%d%d%d%d", &a, &b, &c, &d);
        tribes.emplace_back(a, b, c, d);
    }

    sort(ALL(tribes), [] (const Tribe& t1, const Tribe& t2) {
        return t1.x2 < t2.x2;
    });

#ifdef DBG
    for (int i = 0; i < min(2000, (int) tribes.size()); ++i) {
        fprintf(stderr, "%d %d %d %d\n", tribes[i].x1, tribes[i].x2, tribes[i].y1, tribes[i].y2);
    }
#endif

    sweep();

    // co ja tu robie?
    sort(ALL(tribes), [] (const Tribe& t1, const Tribe& t2) {
        return t1.tuplify() < t2.tuplify();
    });

    vector<tuple<int, int, int, int>> results;
    for (int i = 0; i < tribes.size(); ++i) {
        if (tribes[i].x1 == -1) {
            continue;
        }
        if (i == 0 || tribes[i-1].tuplify() < tribes[i].tuplify()) {
            results.emplace_back(
                    tribes[i].x1, tribes[i].x2, tribes[i].y1, tribes[i].y2);
        }
    }

#ifdef DBG
    for (int i = 0; i < results.size(); ++i) {
        for (int j = 0; j < results.size(); ++j) {
            if (i == j) {
                continue;
            }
            Tribe t1(get<0>(results[i]), get<1>(results[i]), get<2>(results[i]), get<3>(results[i]));
            Tribe t2(get<0>(results[j]), get<1>(results[j]), get<2>(results[j]), get<3>(results[j]));
            if (intersect(t1, t2)) {
                DBGprint("ERROR: %d ([%d-%d] [%d-%d]) %d ([%d-%d] [%d-%d])",
                         i, t1.x1, t1.x2, t1.y1, t1.y2,
                         j, t2.x1, t2.x2, t2.y1, t2.y2);
            }
        }
    }
#endif

    sort(ALL(results));

    printf("%lu\n", results.size());
    for (tuple<int, int, int, int>& t : results) {
        printf("%d %d %d %d\n", get<0>(t), get<1>(t), get<2>(t), get<3>(t));
    }

    memcheck();
}