#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
//const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int n, m; cin >> n >> m;
	vector<tuple<int, int, int>>g;
	rep(i, m) {
		int u, v, c; cin >> u >> v >> c;
		u--, v--, c--;
		g.emplace_back(c, u, v);
	}
	sort(all(g));
	dsu uf(n);
	vector<int>cnt(6);
	for (auto[c, u, v] : g) {
		if (uf.same(u, v))continue;
		uf.merge(u, v);
		cnt[c]++;
	}
	map<vector<int>, double>dp;
	dp[{0, 0, 0, 0, 0, 0}] = 0.0;
	auto dfs = [&](auto &&self, vector<int>arr)->double {
		if (dp.count(arr))return dp[arr];
		int mx = -1;
		int ng = 0;
		double val = 0;
		rep(i, 6) {
			if (arr[i] > 0)mx = i;
			if (mx >= 0) {
				arr[mx]--;
				val += self(self, arr);
				arr[mx]++;
			}
			else {
				ng++;
			}
		}
		val = (val + 6.0) / (6.0 - ng);
		return dp[arr] = val;
	};
	auto ans = dfs(dfs, cnt);
	cout << setprecision(15) << ans << endl;
	return 0;
}