#include <bits/stdc++.h>
#define inf (0x7f7f7f7f)
#define Max(a, b) ((a) > (b) ? (a) : (b))
#define Min(a, b) ((a) < (b) ? (a) : (b))
typedef long long ll;
using namespace std;
template <class T>
inline void read(T &x){
	int ch = 0, f = 0; x = 0;
	for(; !isdigit(ch); ch = getchar()) if(ch == '-') f = 1;
	for(; isdigit(ch); ch = getchar()) x = x * 10 + ch - 48;
	if(f) x = -x;
}
int n,m;
const int N = 1e4 + 5;
struct node{
	int id,deg;
}p[N];
bool cmp(node a,node b){
	return a.deg > b.deg;
}
int main(){
	read(n),read(m);
	for(int i = 0; i < n; i++) p[i].id = i, p[i].deg = 0;
	int a,b;
	for(int i = 1; i <= m; i++){
		read(a),read(b);
		p[a].deg++,p[b].deg++;
	}
	sort(p, p + n, cmp);
	int ans = 0;
	int sum = 2 * m;
	for(int i = 0; i < n; i++){
		if(sum == 2 * n - 2) break;
		if(sum - (p[i].deg - 1) >= 2 * n - 2){
			sum -= (p[i].deg - 1);
			p[i].deg = 1;
			ans++;
		}
		else{
			int delt = sum - (2 * n - 2);
			p[i].deg -= delt;
			ans++;
			break;
		}
	}
	sort(p, p + n, cmp);
	printf("%d\n",ans);
	printf("%d %d\n",n, n - 1);
	int last = 0;
	for(int i = 1; i < n ; i++){
		while(p[last].deg == 0) last++;
		printf("%d %d\n",p[i].id,p[last].id);
		p[last].deg--;
		p[i].deg--;
	}
	return 0;
}