import java.util.*;

public class Main {
	public static void main (String[] args) {
    	Scanner sc = new Scanner(System.in);
    	int n = sc.nextInt();
    	int p = sc.nextInt();
    	int[] dp = new int[p + 5];
    	Arrays.fill(dp, Integer.MAX_VALUE / 2);
    	dp[3] = 0;
    	for (int i = 1; i <= n; i++) {
    	    int zero = sc.nextInt();
    	    int one = sc.nextInt();
    	    int two = sc.nextInt();
    	    for (int j = Math.min(p, i * 3) + 3; j >= 3; j--) {
    	        dp[j] = Math.min(Math.min(dp[j] + zero, dp[j - 1] + one), Math.min(dp[j - 2] + two, dp[j - 3] + 1));
    	    }
    	}
    	System.out.println(dp[p + 3] / (double)n);
	}
}