#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>
#include <queue>
#include <string>
#include <map>
#include <set>
#include <stack>
#include <tuple>
#include <deque>
#include <array>
#include <numeric>
#include <bitset>
#include <iomanip>
#include <cassert>
#include <chrono>
#include <random>
#include <limits>
#include <iterator>
#include <functional>
#include <sstream>
#include <fstream>
#include <complex>
#include <cstring>
#include <unordered_map>
#include <unordered_set>
using namespace std;

using ll = long long;
constexpr int INF = 1001001001;
constexpr int mod = 1000000007;
// constexpr int mod = 998244353;

template<class T>
inline bool chmax(T& x, T y){
    if(x < y){
        x = y;
        return true;
    }
    return false;
}
template<class T>
inline bool chmin(T& x, T y){
    if(x > y){
        x = y;
        return true;
    }
    return false;
}

constexpr ll inf = 1e+15;

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N, P;
    cin >> N >> P;
    vector<int> score(4, 1);
    vector<ll> dp(3 * N + 1, inf);
    dp[0] = 0;
    for(int i = 0; i < N; ++i){
        for(int j = 0; j < 3; ++j)  cin >> score[j];
        vector<ll> dp2(3 * N + 1, inf);
        for(int j = 0; j <= 3 * i; ++j){
            for(int k = 0; k < 4; ++k){
                chmin(dp2[j + k], dp[j] + score[k]);
            }
        }
        swap(dp, dp2);
    }
    double ans = (double)dp[P] / N;
    printf("%.10f\n", ans);

    return 0;
}