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

r=set([0,1,2,3]) - set([a,b,c])
if len(r)==1:
    print(r.pop())
else:
    if a==b==c:print(a)
    else:
        cnt={}
        cnt[a] = cnt.get(a,0)+1
        cnt[b] = cnt.get(b,0)+1
        cnt[c] = cnt.get(c,0)+1
        for i in [a,b,c]:
            if cnt[i]==1:
                print(i)