#include <iostream>
#include <cmath>
#include <string>
#include <algorithm>
#include <set>
#include <vector>
#include <map>
#include <list>
#include <stack>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <queue>
#define mkp make_pair
#define fi first
#define se second
#define pt(num) cout << num << "\n"
#define max(a, b) ((a)>(b) ? (a):(b))
#define min(a, b) ((a)<(b) ? (a):(b))
#define chmax(a, b) (a<b ? a=b : 0)
#define chmin(a, b) (a>b ? a=b : 0)
#define INF 1000000000000000000
#define MOD 1000000007LL
#define MAX 101010
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;
typedef map<ll, ll> Map;


int main(void) {
    ll N, P;
    cin >> N >> P;
    ll i, j;
    ll a[N+5], b[N+5], c[N+5];
    ll dp[P+5];
    
    
    for(i=0; i<N; i++) {
        cin >> a[i] >> b[i] >> c[i];
    }
    
    for(i=1; i<=P; i++)
        dp[i]=INF;
    
    dp[0]=0;
    for(i=0; i<N; i++) {
        for(j=P; j>=0; j--) {
            dp[j]=dp[j]+a[i];
            if(j>=1 && dp[j-1]!=-1)
                chmin(dp[j], dp[j-1]+b[i]);
            if(j>=2 && dp[j-2]!=-1)
                chmin(dp[j], dp[j-2]+c[i]);
            if(j>=3 && dp[j-3]!=-1)
                chmin(dp[j], dp[j-3]+1);
        }
    }
    
    printf("%.10f\n", (double)(dp[P])/(double)N);
    
}