n,p = map(int,input().split())
abc = [list(map(int,input().split()))+[1] for i in range(n)]
inf = float('inf')
#dp[i][j] = i番目まで，解いた数jの時の順位の和の最小値


dp = [[inf]*(max(p+1,4)) for i in range(n)]
dp[0][0] = abc[0][0]
dp[0][1] = abc[0][1]
dp[0][2] = abc[0][2]
dp[0][3] = abc[0][3]
#print(abc)

for i in range(1,n):
    for j in range(p+1):
        for k in range(4):
            if j - k < 0:
                continue
            if dp[i][j]/(i+1) > (dp[i-1][j-k] + abc[i][k])/i:
                dp[i][j] = dp[i-1][j-k] + abc[i][k]
#print(dp)
print(dp[n-1][p]/n)