import java.util.*

fun main(args: Array<String>) {
    val sc = Scanner(System.`in`)
    val (N, P) = Pair(sc.nextInt(), sc.nextInt())
    val q = Array(N, { arrayOf(sc.nextInt(), sc.nextInt(), sc.nextInt(), 1 )})
    var dp = Array(P+4, { 0L })
    val inf = 100000L*N
    val filled_dp = Array(P+1, { inf })
    for (i in 0 until N) {
        val _dp = filled_dp.clone()
        for (j in 0 until 4) {
            for (k in Math.min(4*i, P-j) downTo 0) {
                _dp[k+j] = Math.min(_dp[k+j], dp[k]+q[i][j])
            }
        }
        dp = _dp
    }
    println(dp.take(P+1).min()!!.toDouble() / N.toDouble())
}