#include<bits/stdc++.h>

#define LL long long

#define LD long double

#define fi first

#define se second

#define mk make_pair

#define PLL pair<LL, LL>

#define PLI pair<LL, int>

#define PII pair<int, int>

#define SZ(x) ((int)x.size())

#define ull unsigned long long

using namespace std;

const int N =  + ;

const int inf = 0x3f3f3f3f;

const LL INF = 0x3f3f3f3f3f3f3f3f;

const int mod = 1e9 + ;

const double eps = 1e-;

const double PI = acos(-);

template<class T, class S> inline void add(T& a, S b) {a += b; if(a >= mod) a -= mod;}

template<class T, class S> inline void sub(T& a, S b) {a -= b; if(a < ) a += mod;}

template<class T, class S> inline bool chkmax(T& a, S b) {return a < b ? a = b, true : false;}

template<class T, class S> inline bool chkmin(T& a, S b) {return a > b ? a = b, true : false;}

int n, m, num1, num2;

int cnt[N];

int need[N];

bool have[N];

vector<PII> vc;

double dp[N][N];

double sum[N];

double calc(int n, int m) {

    return exp(sum[m] + sum[n - m] - sum[n]);

}

int main() {

    for(int i = ; i < N; i++) sum[i] = sum[i - ] + log(i);

    scanf("%d%d", &n, &m);

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

        scanf("%d", &cnt[i]);

        for(int j = ; j <= cnt[i]; j++) {

            int x; scanf("%d", &x);

            vc.push_back(mk(x, i));

        }

    }

    sort(vc.rbegin(), vc.rend());

    int val = vc[n - ].fi;

    num1 = n; num2 = ;

    if(SZ(vc) == n || vc[n].fi != val) val = -;

    if(~val) {

        for(auto& t : vc) {

            if(t.fi > val) need[t.se]++, num1--;

            else if(t.fi == val) have[t.se] = true, num2++;

            else break;

        }

    } else {

        for(int i = ; i < n; i++) need[vc[i].se]++;

        num1 = , num2 = ;

    }

    dp[][] = 1.0;

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

        for(int j = ; j <= i && j <= num1; j++) {

            if(!have[i]) {

                dp[i][j] = dp[i - ][j] * calc(cnt[i], need[i]);

            }

            else {

                if(j) dp[i][j] = dp[i - ][j] * calc(cnt[i], need[i]) + dp[i - ][j - ] * calc(cnt[i], need[i] + );

                else dp[i][j] = dp[i - ][j] * calc(cnt[i], need[i]);

            }

        }

    }

    printf("%.15f\n", dp[m][num1] * calc(num2, num1));

    return ;

}

/*

*/