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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<cstdlib>
#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 lowbit(x) (x&(-x))
#define mid (x+y>>1)
#define sqr(x) ((x)*(x))
#define NM 1005
#define nm 67108864
using namespace std;
const double pi=acos(-1);
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 a[NM],ans;
char d[nm];
char Max(int x,int y){return x>y?x:y;}
int main(){
n=read();m=read();
inc(i,1,m){
_x=read();_y=read();
a[_x]|=succ(_y);a[_y]|=succ(_x);
}
inc(i,0,n-1)a[i]|=succ(i);
tot=succ(n)-1;
inc(i,1,tot)d[i]=Max(d[i^lowbit(i)],d[i&(~a[__builtin_ctz(i)])]+1),ans+=d[i];
printf("%d\n",ans);
return 0;
}
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