Kertoma

counts = [int(x) for x in input().split(" ")]

from math import ceil, log

def get_log10_power_of_n_factorial(n):
    thisislog10 = 0
    for i in range(1, n+1):
        thisislog10 += log(i, 10)
    return thisislog10

s = sum(counts)

for i in range(60010):
    if(s == ceil(get_log10_power_of_n_factorial(i))):
        print(i)
        break