import java.util.*;
import java.io.*;

public class Main {
    static int[][] points;
    static ArrayList<HashMap<Integer, Integer>> dp = new ArrayList<>();
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int p = sc.nextInt();
        points = new int[n][4];
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < 3; j++) {
                points[i][j] = sc.nextInt();
            }
            points[i][3] = 1;
            dp.add(new HashMap<>());
        }
        double all = dfw(n - 1, p);
        System.out.println(all / n);
    }
    
    static int dfw(int idx, int p) {
        if (p < 0) {
            return Integer.MAX_VALUE / 2;
        }
        if (idx < 0) {
            return 0;
        }
        if ((idx + 1) * 3 <= p) {
            return idx + 1;
        }
        if (!dp.get(idx).containsKey(p)) {
            int value = Integer.MAX_VALUE;
            for (int i = 0; i < 4; i++) {
                value = Math.min(value, dfw(idx - 1, p - i) + points[idx][i]);
            }
            dp.get(idx).put(p, value);
        }
        return dp.get(idx).get(p);
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String nextLine() throws Exception {
        return br.readLine();
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}