a,b,c = map(int,input().split())
fruits = [a,b,c]
fruits.sort()
num_list = [0,1,2,3]
if fruits[0] == fruits[2]:
    print(a)
elif fruits[0]==fruits[1] and fruits[0]!=fruits[2]:
    print(fruits[2])
elif fruits[0]!=fruits[1] and fruits[1]==fruits[2]:
    print(fruits[0])
else:
    num_list.remove(a)
    num_list.remove(b)
    num_list.remove(c)
    print(num_list[0])