import sys
#input = sys.stdin.readline
input = sys.stdin.buffer.readline #文字列はダメ
#sys.setrecursionlimit(1000000)
#import bisect
#import itertools
#import random
#from heapq import heapify, heappop, heappush
#from collections import defaultdict 
#from collections import deque
#import copy
#import math
#from functools import lru_cache
#@lru_cache(maxsize=None)
#MOD = pow(10,9) + 7
#MOD = 998244353
#dx = [1,0,-1,0]
#dy = [0,1,0,-1]
#dx8 = [1,1,0,-1,-1,-1,0,1]
#dy8 = [0,1,1,1,0,-1,-1,-1]

def main():
    a,b,c = map(int,input().split())
    if a == b == c:
        print(a)
    elif a != b and b != c and c != a:
        print(6-(a+b+c))
    else:
        if a == b:
            print(c)
        elif b == c:
            print(a)
        elif c == a:
            print(b)
        
                
if __name__ == '__main__':
    main()