#include <bits/stdc++.h>
using namespace std;
#include <atcoder/dsu>

#define rep(i, l, r) for (int i = (int)(l); i<(int)(r); i++)
#define ll long long

int main() {
    int N, M; cin >> N >> M;

    vector<tuple<int, int, int>> Edges(M);
    rep(i, 0, M) {
        int u, v, c; cin >> u >> v >> c;
        u--; v--; c--;
        Edges[i] = {c, u, v};
    }

    array<int, 6> cnt = {0, 0, 0, 0, 0, 0};
    atcoder::dsu d(N);

    sort(Edges.begin(), Edges.end());
    for (int i = 0; i < M; i++) {
        auto[c, u, v] = Edges[i];
        if (!d.same(u, v)) {
            d.merge(u, v);
            cnt[c]++;
        }
    }

    map<array<int, 6>, double> dp;
    //すでにこれだけ集めたときの残り回数の期待値
    array<int, 6> A;
#define FOR(x) for (A[x] = cnt[x]; A[x] >= 0; A[x]--)
    FOR(0) FOR(1) FOR(2) FOR(3) FOR(4) FOR(5) {
#undef FOR
        int loop = 0;
        double t = 0;
        rep(i, 0, 6) {
            //iの目が出たとする
            //使える中で最上位に使うのが最適
            bool used = false;
            array<int, 6> B = A;
            for (int j = i; j >= 0; j--) {
                if (B[j] < cnt[j]) {
                    B[j]++;
                    t += dp[B];
                    used = true;
                    break;
                }
            }
            if (!used) loop++;
        }
        if (loop == 6) {
            dp[A] = 0;
            continue;
        }
        dp[A] = (t+6)/(6-loop);
    }
    cout << fixed << setprecision(15) << dp[{0, 0, 0, 0, 0, 0}] << endl;
}