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#include <bits/stdc++.h>

#define FWD(a,b,c) for(int a=(b); a<(c); ++a)
#define BCK(a,b,c) for(int a=(b); a>(c); --a)
#define x first
#define y second

using namespace std;

typedef pair<int, int> PII;

struct rectangle{
	int x1, y1, x2, y2;
	rectangle(){}
	rectangle(int a, int b, int c, int d) : x1(a), y1(b), x2(c), y2(d) {}
};

inline rectangle operator+(const rectangle &a, const rectangle &b){
	return rectangle(min(a.x1, b.x1), min(a.y1, b.y1), max(a.x2, b.x2), max(a.y2, b.y2));
}

inline bool cmpFinal(const rectangle &a, const rectangle &b){
	if(a.x1 == b.x1){
		if(a.x2 == b.x2){
			if(a.y1 == b.y1)
				return a.y2 < b.y2;
			return a.y1 < b.y1;
		}
		return a.x2 < b.x2;
	}
	return a.x1 < b.x1;
}

inline bool cmpSweep(const rectangle &a, const rectangle &b){
	return a.x2 < b.x2;
}

const int d = 1024*1024;
vector<rectangle> rects;
vector<int> hbars[2*d+3];
vector<int> vbars[2*d+3];
vector<bool> deleted;
vector<rectangle> res;

inline void addhbar(int p, int i){
	p += d;
	while(p){
		hbars[p].push_back(i);
		p /= 2;
	}
}

inline int gethbar(int p, int q){
	p += d;
	q += d;
	int r = -1;
	while(p < q){
		if(p&1){
			while(!hbars[p].empty() && deleted[hbars[p].back()]) hbars[p].pop_back();
			if(!hbars[p].empty()) r = max(r, hbars[p].back());
			++p;
		}
		if((q&1)==0){
			while(!hbars[q].empty() && deleted[hbars[q].back()]) hbars[q].pop_back();
			if(!hbars[q].empty()) r = max(r, hbars[q].back());
			--q;
		}
		p /= 2; q /= 2;
	}
	if(p == q){
		while(!hbars[p].empty() && deleted[hbars[p].back()]) hbars[p].pop_back();
		if(!hbars[p].empty()) r = max(r, hbars[p].back());
	}
	return r;
}

inline void addvbar(int p, int q, int i){
	p += d;
	q += d;
	while(p < q){
		if(p&1){
			vbars[p].push_back(i);
			++p;
		}
		if((q&1)==0){
			vbars[q].push_back(i);
			--q;
		}
		p /= 2; q /= 2;
	}
	if(p == q)
		vbars[p].push_back(i);
}

inline int getvbar(int p){
	p += d;
	int r = -1;
	while(p){
		while(!vbars[p].empty() && deleted[vbars[p].back()]) vbars[p].pop_back();
		if(!vbars[p].empty()) r = max(r, vbars[p].back());
		p /= 2;
	}
	return r;
}

inline void usun(int i){
	deleted[i] = 1;
}

inline void wrzuc(int i){
	deleted.push_back(0);
	addhbar(rects[i].y1, i);
	addhbar(rects[i].y2, i);
	addvbar(rects[i].y1, rects[i].y2, i);;
}

void sweep(){
	sort(rects.begin(), rects.end(), cmpSweep);
	FWD(i,0,(int)rects.size()){
		for(;;){
			//printf("%d: %d %d %d %d\n", i, rects[i].x1, rects[i].x2, rects[i].y1, rects[i].y2);
			int s = gethbar(rects[i].y1, rects[i].y2);
			s = max(s, getvbar(rects[i].y1));
			s = max(s, getvbar(rects[i].y2));
			if(s != -1 && rects[s].x2 >= rects[i].x1){
				//printf("merge z %d\n", s);
				usun(s);
				rects[i] = rects[i] + rects[s];
			}else
				break;
		}
		wrzuc(i);
	}
	FWD(i,0,(int)rects.size())
		if(!deleted[i])
			res.push_back(rects[i]);
}

int main(){
	int n;
	scanf("%d", &n);
	FWD(i,0,n){
		rectangle r;
		scanf("%d %d %d %d", &r.x1, &r.x2, &r.y1, &r.y2);
		assert(r.x1 < r.x2);
		assert(r.y1 < r.y2);
		--r.x2;
		--r.y2;
		rects.push_back(r);
	}
	sweep();
	for(rectangle &r : res){
		++r.x2;
		++r.y2;
	}
	sort(res.begin(), res.end(), cmpFinal);
	printf("%d\n", (int)res.size());
	for(rectangle r : res)
		printf("%d %d %d %d\n", r.x1, r.x2, r.y1, r.y2);
	return 0;
}