# coding: utf-8

#l, k = map(int,input().split())
#l = int(input())
#N = int(input())
B = list(map(int,input().split()))

l = [i for i in range(1,11)]
#print(l)
for a in B:
    if a in l:
        l[a-1] = 0
l.sort()
print(l[-1])