#include <bits/stdc++.h>
#define REP(i, s, n) for (int i = s; i < n; i++)
#define ALL(a) a.begin(), a.end()
#define MOD 1000000007
using namespace std;
typedef long long ll;

int main() {
    int N, P; cin >> N >> P;
    vector<int> A(N), B(N), C(N);
    REP(i, 0, N) cin >> A[i] >> B[i] >> C[i];

    vector<int> dp(P + 1, 1 << 30);
    dp[0] = 0;
    REP(i, 0, N) {
        for (int j = P; j >= 0; j--) {
            if (j + 1 <= P) dp[j + 1] = min(dp[j + 1], dp[j] + B[i]);
            if (j + 2 <= P) dp[j + 2] = min(dp[j + 2], dp[j] + C[i]);
            if (j + 3 <= P) dp[j + 3] = min(dp[j + 3], dp[j] + 1);
            dp[j] = dp[j] + A[i];
        }

        // cout << "i : " << i << " : ";
        // REP(i, 0, P + 1) {
        //     cout << setw(12) << setfill(' ') << dp[i];
        // }
        // cout << endl;
    }

    cout << fixed << setprecision(15);
    cout << (double)dp[P] / N << endl;
    return 0;
}