import sys

readline = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)


def main():
    N = int(readline())
    A = list(map(int, readline().split()))
    S = set(A)

    if len(S) == N:
        print("YES")
    else:
        print("NO")


if __name__ == '__main__':
    main() import sys sys readline = sys.stdin.readline readline sys.stdin.readline sys.stdin sys stdin readline MOD = 10 ** 9 + 7 MOD 10 ** 9 + 7 10 ** 9 10 9 7 INF = float('INF') INF float('INF') float 'INF' sys.setrecursionlimit(10 ** 5) sys.setrecursionlimit sys setrecursionlimit 10 ** 5 10 5 def main():
    N = int(readline())
    A = list(map(int, readline().split()))
    S = set(A)

    if len(S) == N:
        print("YES")
    else:
        print("NO") main N = int(readline()) N int(readline()) int readline() readline A = list(map(int, readline().split())) A list(map(int, readline().split())) list map(int, readline().split()) map int readline().split() ().split () readline split S = set(A) S set(A) set A if len(S) == N:
        print("YES")
    else:
        print("NO") len(S) == N len(S) len S N print("YES") print "YES" print("NO") print "NO" if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main readline = sys.stdin.readline sys.stdin.readline readline MOD = 10 ** 9 + 7 10 ** 9 + 7 MOD def main():
    N = int(readline())
    A = list(map(int, readline().split()))
    S = set(A)

    if len(S) == N:
        print("YES")
    else:
        print("NO") def main():
    N = int(readline())
    A = list(map(int, readline().split()))
    S = set(A)

    if len(S) == N:
        print("YES")
    else:
        print("NO") main INF = float('INF') float('INF') INF
import sys

readline = sys.stdin.readline
MOD = 10 ** 9 + 7
INF = float('INF')
sys.setrecursionlimit(10 ** 5)


def main():
    N = int(readline())
    A = list(map(int, readline().split()))
    S = set(A)

    if len(S) == N:
        print("YES")
    else:
        print("NO")


if __name__ == '__main__':
    main()
