#include<iostream>
#include <algorithm>
#include <functional>
#include<vector>
#include<math.h>
#include <assert.h>
#include<bitset>
#include<string>
#include <deque>
#include<queue>
#include <iomanip>
#include<map>
#include <random>
#include<type_traits>
#include<stack>
#include <sstream> 
#include <limits>
#include <numeric>
#include<string.h>
#include<set>
#include <climits>
using namespace std;
typedef unsigned long long ull;
#define ll long long int
ll mod = 1000000007;
//typedef vector<int> V;
//typedef vector<V> VV;
//typedef vector<VV> VVV;




ll a[5003], b[5003], c[5003],dp[5003][15004];

int main() {
	ll n, p;
	cin >> n >> p;
	for (int i = 1; i <= n; i++) {
		cin >> a[i] >> b[i] >> c[i];
	}
	for (int i = 0; i <= n; i++) {
		for (int j = 0; j <= p; j++) {
			dp[i][j] = 10000000000000000;
		}
	}
	dp[0][0] = 0;
	for (int i = 1; i <= n; i++) {
		for (int j = 0; j <= p; j++) {
			dp[i][j] = dp[i - 1][j]+a[i];
			if(j-1>=0)dp[i][j] = min(dp[i][j], dp[i - 1][j - 1]+b[i]);
			if(j-2>=0)dp[i][j] = min(dp[i][j], dp[i - 1][j - 2]+c[i]);
		}
	}
	long double y=(double)dp[n][p];
	cout << y/n << endl;
}