#include<cstdio>
#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
using namespace std;
typedef vector<__float128> ploy;
ploy operator + (ploy x,ploy y){ploy ans(max(x.size(),y.size()),0);for (int i=0;i<ans.size();i++) {if (i<x.size()) ans[i]+=x[i];if (i<y.size()) ans[i]+=y[i];}return ans;
}
ploy operator - (ploy x,ploy y) {ploy ans(max(x.size(),y.size()),0);for (int i=0;i<ans.size();i++) {if (i<x.size()) ans[i]+=x[i];if (i<y.size()) ans[i]-=y[i];}return ans;
}
ploy operator * (ploy x,ploy y) {ploy ans(x.size()+y.size()-1,0);for (int i=0;i<x.size();i++) for (int j=0;j<y.size();j++) ans[i+j]+=x[i]*y[j];return ans;
}
bool b[1040];
ploy f[1040],quick[100];
int n,m;
struct edges{int x,y;}e[100];
ploy ONE(1,1);
inline void print(ploy x){printf("%d\n",x.size());for (int i=0;i<x.size();i++) printf("%lf ",double(x[i]));printf("\n");
}
void dp(int x){if (b[x]) return ;b[x]=1;ploy tmp(0,0);for (int i=1;i<(1<<n);i++) {if (!(i&1)) continue;if ((i&x)!=i) continue;if (i==x) continue;int j=x^i;int cnt=0;for (int k=1;k<=m*2;k++) if (i&(1<<e[k].x)&&j&(1<<e[k].y)) cnt++;dp(i);tmp=tmp+f[i]*quick[cnt];}f[x]=ONE-tmp;
}
__float128 cal(ploy x) {__float128 ans=0;for (int i=0;i<x.size();i++) ans+=x[i]*1.0/(i+1);return ans;
}
int main()    {scanf("%d%d",&n,&m);quick[0]=ONE;quick[1]=ploy(2,0);quick[1][0]=1;quick[1][1]=-1;for (int i=2;i<=m;i++) quick[i]=quick[i-1]*quick[1];for (int i=1;i<=m;i++) {int x,y;scanf("%d%d",&x,&y);x--,y--;e[i*2-1]=(edges){x,y};e[i*2]=(edges){y,x};}b[1]=1;f[1]=ONE;dp((1<<n)-1);ploy ans=ONE-f[(1<<n)-1];printf("%.6lf\n",double(cal(ans)));return 0;
}