k = int(input())
def sn(x):
    sum = 0
    for i in range (1, x + 1):
        a = 1 / i
        i = i + 1
        sum = sum + a
    return sum
n = 1
while 0 == 0:
    if sn(n) > k:
        print(n)
        break
    else:
        n = n +1