if __name__ == '__main__':
    nbInt = input()
    test = sorted(input().split(" "))

    for i in range(0, len(test)):
        if test.count(test[i]) == 1:
            print(test[i])
# Y a surement moyen d'optimiser ça...
          

0e73c38d14c70ea553a9aa68284be1bbd2b821dd
<mask token>

if __name__ == '__main__':
    nbInt = input()
    test = sorted(input().split(' '))
    for i in range(0, len(test)):
        if test.count(test[i]) == 1:
            print(test[i])

if __name__ == '__main__':
    nbInt = input()
    test = sorted(input().split(" "))

    for i in range(0, len(test)):
        if test.count(test[i]) == 1:
            print(test[i])
# Y a surement moyen d'optimiser ça...
          
