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
/* 2024
 * Maciej Szeptuch
 */
#include <algorithm>
#include <cstdio>
#include <queue>
#include <set>
#include <vector>

const int MAX_ACTIONS = 200001;
const int MAX_ATOMS = 30001;
const int MAX_BONDS = 50001;

using Bond = std::pair<int, int>;
using Path = std::vector<int>;

int actions;
int atoms;
int source_bonds;
int target_bonds;
Bond source_bond[MAX_BONDS];
Bond target_bond[MAX_BONDS];
std::pair<bool, Bond> action[MAX_ACTIONS];
std::set<int> graph[MAX_ATOMS];

void remove_bond(const Bond &bond);
void add_bond(const Bond &bond);

Path find_path(const int s, const int e);
void connect_path(const Path &path, int s = 0, int e = -1);
void disconnect_path(const Path &path, int s = 0, int e = -1);

void add_edge(const int s, const int e);
void remove_edge(const int s, const int e);

int main(void)
{
    scanf("%d %d", &atoms, &source_bonds);
    for(int b = 0; b < source_bonds; ++b)
    {
        scanf("%d %d", &source_bond[b].first, &source_bond[b].second);
        if(source_bond[b].second < source_bond[b].first)
            std::swap(source_bond[b].first, source_bond[b].second);

        graph[source_bond[b].first].insert(source_bond[b].second);
        graph[source_bond[b].second].insert(source_bond[b].first);
    }

    scanf("%d", &target_bonds);
    for(int b = 0; b < target_bonds; ++b)
    {
        scanf("%d %d", &target_bond[b].first, &target_bond[b].second);
        if(target_bond[b].second < target_bond[b].first)
            std::swap(target_bond[b].first, target_bond[b].second);
    }

    std::sort(source_bond, source_bond + source_bonds);
    std::sort(target_bond, target_bond + target_bonds);

    int sb = 0;
    int tb = 0;
    while(sb < source_bonds && tb < target_bonds)
    {
        if(source_bond[sb] == target_bond[tb])
        {
            ++sb;
            ++tb;
            continue;
        }

        if(source_bond[sb] < target_bond[tb])
        {
            ++sb;
            continue;
        }

        add_bond(target_bond[tb]);
        ++tb;
    }

    while(tb < target_bonds)
    {
        add_bond(target_bond[tb]);
        ++tb;
    }

    sb = 0;
    tb = 0;
    while(sb < source_bonds && tb < target_bonds)
    {
        if(source_bond[sb] == target_bond[tb])
        {
            ++sb;
            ++tb;
            continue;
        }

        if(source_bond[sb] < target_bond[tb])
        {
            remove_bond(source_bond[sb]);
            ++sb;
            continue;
        }

        ++tb;
    }

    while(sb < source_bonds)
    {
        remove_bond(source_bond[sb]);
        ++sb;
    }

    printf("%d\n", actions);
    for(int a = 0; a < actions; ++a)
        printf("%c %d %d\n", action[a].first ? '+' : '-', action[a].second.first, action[a].second.second);

    return 0;
}

inline void remove_bond(const Bond &bond)
{
    Path path = find_path(bond.first, bond.second);
    connect_path(path);
    remove_edge(bond.first, bond.second);
    disconnect_path(path);
}

inline void add_bond(const Bond &bond)
{
    Path path = find_path(bond.first, bond.second);
    connect_path(path);
    add_edge(bond.first, bond.second);
    disconnect_path(path);
}

inline Path find_path(const int s, const int e)
{
    std::vector<int> prev(atoms, 0);
    std::queue<int> que;
    que.push(s);
    while(!que.empty())
    {
        int v = que.front();
        que.pop();

        for(auto n: graph[v])
        {
            if(prev[n])
                continue;

            if(v == s && n == e)
                continue;

            if(n == e)
            {
                Path path{e};
                for(int p = v; p != s; p = prev[p])
                    path.push_back(p);

                path.push_back(s);
                std::reverse(std::begin(path), std::end(path));
                return path;
            }

            prev[n] = v;
            que.push(n);
        }
    }

    return {};
}

inline void connect_path(const Path &path, int s, int e)
{
    if(e == -1)
        e = path.size() - 1;

    if(e - s <= 2)
        return;

    if(e - s > 3)
    {
        connect_path(path, s, (s + e) / 2);
        add_edge(path[s], path[(s + e) / 2]);
    }

    connect_path(path, (s + e) / 2, e);
    add_edge(path[(s + e) / 2], path[e]);
}

inline void disconnect_path(const Path &path, int s, int e)
{
    if(e == -1)
        e = path.size() - 1;

    if(e - s <= 2)
        return;

    remove_edge(path[(s + e) / 2], path[e]);
    disconnect_path(path, (s + e) / 2, e);
    if(e - s > 3)
    {
        remove_edge(path[s], path[(s + e) / 2]);
        disconnect_path(path, s, (s + e) / 2);
    }
}

inline void add_edge(const int s, const int e)
{
    graph[s].insert(e);
    graph[e].insert(s);
    action[actions++] = {true, {s, e}};
}

inline void remove_edge(const int s, const int e)
{
    graph[s].erase(e);
    graph[e].erase(s);
    action[actions++] = {false, {s, e}};
}