import std.stdio, std.array, std.string, std.conv, std.algorithm;
import std.typecons, std.range, std.random, std.math, std.container;
import std.numeric, std.bigint, core.bitop, core.stdc.stdio;


void main() {
    alias Tuple!(int, "score", int, "solved", int, "index") node;
    int N, P, a, b, c;
    scanf("%d %d", &N, &P);
    auto A = new int[][](N, 4);
    node[] B;

    foreach (i; 0..N) {
        scanf("%d %d %d", &a, &b, &c);
        A[i] = [a, b, c, 1];
        foreach (j; 0..4)
            B ~= node(A[i][j]-A[i][0], j, i);
    }

    B.sort!"a.score < b.score"();

    auto solved = new int[](N);
    foreach (i; 0..N) solved[i] = -1;

    foreach (x; B) {
        if (solved[x.index] > -1)
            continue;
        if (x.solved > P)
            continue;
        P -= x.solved;
        solved[x.index] = x.solved;
    }

    long ans = 0;
    foreach (i; 0..N)
        ans += A[i][solved[i]];
    writefln("%.10f", 1.0L * ans / N);
}