arr = map(int, input().split())

cur_set = set()
mn = 1e9
mx = -1e9

for elem in arr:
    cur_set.add(elem)
    mn = min(mn, elem)
    mx = max(mx, elem)

full_set = {i for i in range(mn, mx + 1)}
print(*full_set.symmetric_difference(cur_set))