#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

#include <cmath>

using namespace std;

typedef long long ll;

const int N=,S=<<;

inline int read(){

    char c=getchar();int x=,f=;

    while(c<''||c>''){if(c=='-')f=-;c=getchar();}

    while(c>=''&&c<=''){x=x*+c-'';c=getchar();}

    return x*f;

}

int m,n,val[N],need[N];

double f[N][S];

int main(){

    freopen("in","r",stdin);

    m=read();n=read();

    for(int i=;i<n;i++){

        val[i]=read();int x=read();

        while(x) need[i]|=(<<(x-)),x=read();

    }

    int All=<<n;

    for(int i=m;i>=;i--)

        for(int s=;s<All;s++){

            for(int j=;j<n;j++){

                if((s&need[j])==need[j]) f[i][s]+=max(f[i+][s],f[i+][s|(<<j)]+val[j]);

                else f[i][s]+=f[i+][s];

            }

            f[i][s]/=n;

        }

    printf("%.6lf",f[][]);

}