#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <chrono>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")


vector<int> uf;
int root(int u) {
  return (uf[u] < 0) ? u : (uf[u] = root(uf[u]));
}
bool connect(int u, int v) {
  u = root(u);
  v = root(v);
  if (u == v) return false;
  if (uf[u] > uf[v]) swap(u, v);
  uf[u] += uf[v];
  uf[v] = u;
  return true;
}


using Double = long double;

constexpr int K = 6;

int N, M;
vector<int> A, B, C;

int main() {
  for (; ~scanf("%d%d", &N, &M); ) {
    A.resize(M);
    B.resize(M);
    C.resize(M);
    for (int i = 0; i < M; ++i) {
      scanf("%d%d%d", &A[i], &B[i], &C[i]);
      --A[i];
      --B[i];
      --C[i];
    }
    
    vector<pair<int, int>> cis(M);
    for (int i = 0; i < M; ++i) cis[i] = make_pair(C[i], i);
    sort(cis.begin(), cis.end());
    uf.assign(N, -1);
    int F[K] = {};
    for (const auto &ci : cis) {
      const int i = ci.second;
      if (connect(A[i], B[i])) {
        ++F[C[i]];
      }
    }
cerr<<"F = ";pv(F,F+K);
    
    int G[K + 1];
    G[0] = 1;
    for (int k = 0; k < K; ++k) G[k + 1] = G[k] * (F[k] + 1);
    
    vector<Double> dp(G[K], 0);
    for (int u = 1; u < G[K]; ++u) {
      int xs[K];
      for (int k = 0; k < K; ++k) xs[k] = u / G[k] % (F[k] + 1);
      int hazure = 0;
      for (int k = K - 1, l = K - 1; k >= 0; --k) {
        // k: deta, l: kesu
        for (chmin(l, k); l >= 0 && !xs[l]; --l) {}
        if (l >= 0) {
          dp[u] += dp[u - G[l]];
        } else {
          ++hazure;
        }
      }
      dp[u] += K;
      dp[u] /= (K - hazure);
    }
    printf("%.12Lf\n", dp.back());
  }
  return 0;
}