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#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<queue>
#include<map>
#include<stack>
#include<cmath>
#include<set>
#include<bitset>
#include<complex>
#include<assert.h>
#define inc(i,l,r) for(int i=l;i<=r;i++)
#define dec(i,l,r) for(int i=l;i>=r;i--)
#define link(x) for(edge *j=h[x];j;j=j->next)
#define mem(a) memset(a,0,sizeof(a))
#define ll long long
#define eps 1e-8
#define succ(x) (1<<x)
#define mid (x+y>>1)
#define lowbit(x) (x&(-x))
#define sqr(x) ((x)*(x))
#define NM 15
#define nm 20005
using namespace std;
const double pi=acos(-1);
const int inf=1e9+7;
ll read(){
ll x=0,f=1;char ch=getchar();
while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
return f*x;
}
int n,m,_x,_y,tot;
int d[NM][NM][nm],f[NM][NM][nm],g[nm];
struct tmp{int x,y,t;}pre[nm];
bool a[NM][NM];
void out(int x,int y,int t){
for(int p=f[x][y][t];__builtin_popcount(t)>1;y=p,p=f[x][y][t]){
printf("%d %d\n",p,y);
if(x!=y)t^=succ(y-1);
}
}
int main(){
n=read();m=read();
inc(i,1,m){
_x=read();_y=read();
a[_x][_y]++;a[_y][_x]++;
}
tot=succ(n)-1;
inc(j,0,tot)g[j]=inf;
inc(p,1,n){
inc(i,1,n)inc(j,0,tot)d[p][i][j]=inf;
d[p][p][succ(p-1)]=0;
inc(j,0,tot)if(j&succ(p-1)){
inc(i,1,n)if(d[p][i][j]<inf&&(p!=i||j==succ(p-1))){
if(__builtin_popcount(j)>2&&a[i][p]){
if(g[j]>d[p][i][j]+1){
g[j]=d[p][i][j]+1;
pre[j]=tmp{p,i,j};
}
}
inc(k,1,n)if(a[i][k]&&((j&succ(k-1))==0||(k==p&&__builtin_popcount(j)>2))){
if(d[p][k][j|succ(k-1)]>d[p][i][j]+1){
d[p][k][j|succ(k-1)]=d[p][i][j]+1;
f[p][k][j|succ(k-1)]=i;
}
}
}
}
}
inc(i,0,tot)if(g[i]<inf){
inc(x,1,n)if(i&succ(x-1))inc(y,1,n)if(i&succ(y-1)){
int t=tot^i;
for(int j=t;j;j=t&(j-1)){
if(g[i|j]>g[i]+d[x][y][j|succ(x-1)|succ(y-1)]){
g[i|j]=g[i]+d[x][y][j|succ(x-1)|succ(y-1)];
pre[i|j]=tmp{x,y,j|succ(x-1)|succ(y-1)};
}
}
}
}
printf("%d\n",g[tot]);
while(__builtin_popcount(tot)>2){
out(pre[tot].x,pre[tot].y,pre[tot].t);
tot=tot^pre[tot].t|succ(pre[tot].x-1)|succ(pre[tot].y-1);
}
inc(i,1,n)if(tot&succ(i-1)){
inc(j,i+1,n)if(tot&succ(j-1)){
printf("%d %d\n",i,j);
break;
}
break;
}
return 0;
}
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