from collections import Counter as c

def lonelyinteger(a):
    b = c(a)
    r = [i for i,j in b.items() if j == 1]
    return print(*r)

if __name__ == '__main__':
    n = int(input().strip())
    a = list(map(int, input().rstrip().split()))
    lonelyinteger(a)