def f(a,b,c):
    X=[a,b,c]

    # 4 of a kind
    for k in range(4):
        if X.count(k)==3:
            return k

    # 2 pair
    for i in range(4):
        for j in range(4):
            if X.count(i)==2 and X.count(j)==1:
                return j

    # high card
    for i in range(4):
        if X.count(i)==0:
            return i

a,b,c=map(int,input().split())

print(f(a,b,c))