num = int(input())
nums = []
for i in range(num):
    nums_2 = []
    n = input().split()
    if float(n[-1]) > 100:
        snak = 0
    else:
        snak = 1 - int(n[-1]) / 100
    for d in range(len(n) - 1):
        nums_2.append(float(n[d]) * snak)
    nums.append(nums_2)
n = float(input()) - 1
number = 0
for t in range(len(nums)):
    if len(nums[t]) >= n:
        nums_2 = nums[t]
        for s in range(len(nums_2)):
            if s == n:
                number += float(nums_2[s])
if number % 1 == 0:
    number = int(number)
print(number)