1 /**************************************************************
 2     Problem: 1076
 3     User: Tunix
 4     Language: C++
 5     Result: Accepted
 6     Time:1336 ms
 7     Memory:52984 kb
 8 ****************************************************************/
 9  
10 //BZOJ 1076
11 #include<cstdio>
12 #include<cstdlib>
13 #include<cstring>
14 #include<iostream>
15 #include<algorithm>
16 #define rep(i,n) for(int i=0;i<n;++i)
17 #define F(i,j,n) for(int i=j;i<=n;++i)
18 #define D(i,j,n) for(int i=j;i>=n;--i)
19 using namespace std;
20  
21 int getint(){
22     int v=0,sign=1; char ch=getchar();
23     while(ch<‘0‘||ch>‘9‘) {if (ch==‘-‘) sign=-1; ch=getchar();}
24     while(ch>=‘0‘&&ch<=‘9‘) {v=v*10+ch-‘0‘; ch=getchar();}
25     return v*=sign;
26 }
27 /*******************tamplate********************/
28 const int N=101,M=(1<<16);
29 double f[N][M];
30 int w[16],d[16],n,K;
31 int main(){
32 //  freopen("input.txt","r",stdin);
33     K=getint(); n=getint();
34     int t;
35     F(i,1,n){
36         w[i]=getint();
37         t=getint();
38         while(t){ d[i]|=1<<(t-1); t=getint();}
39     }
40     D(i,K,1)
41         rep(j,1<<n){
42             F(k,1,n)
43                 if ( (d[k]&j)==d[k] )
44                     f[i][j]+=max(f[i+1][j],f[i+1][j|(1<<(k-1))]+w[k]);
45                 else f[i][j]+=f[i+1][j];
46             f[i][j]/=n;
47         }
48     printf("%.6lf",f[1][0]);
49     return 0;
50 }