def distinct_or_not():
    # 入力
    N = int(input())
    A = list(map(int, input().split()))
    # Aを集合型に変換
    A_set = set(A)
    # AとA_setを比較
    if len(A) == len(A_set):
        return 'YES'
    else:
        return 'NO'

result = distinct_or_not()
print(result) def distinct_or_not():
    # 入力
    N = int(input())
    A = list(map(int, input().split()))
    # Aを集合型に変換
    A_set = set(A)
    # AとA_setを比較
    if len(A) == len(A_set):
        return 'YES'
    else:
        return 'NO' distinct_or_not N = int(input()) N int(input()) int input() input A = list(map(int, input().split())) A list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () input split A_set = set(A) A_set set(A) set A if len(A) == len(A_set):
        return 'YES'
    else:
        return 'NO' len(A) == len(A_set) len(A) len A len(A_set) len A_set return 'YES' 'YES' return 'NO' 'NO' result = distinct_or_not() result distinct_or_not() distinct_or_not print(result) print result def distinct_or_not():
    # 入力
    N = int(input())
    A = list(map(int, input().split()))
    # Aを集合型に変換
    A_set = set(A)
    # AとA_setを比較
    if len(A) == len(A_set):
        return 'YES'
    else:
        return 'NO' def distinct_or_not():
    # 入力
    N = int(input())
    A = list(map(int, input().split()))
    # Aを集合型に変換
    A_set = set(A)
    # AとA_setを比較
    if len(A) == len(A_set):
        return 'YES'
    else:
        return 'NO' distinct_or_not result = distinct_or_not() distinct_or_not() result
def distinct_or_not():
    # 入力
    N = int(input())
    A = list(map(int, input().split()))
    # Aを集合型に変換
    A_set = set(A)
    # AとA_setを比較
    if len(A) == len(A_set):
        return 'YES'
    else:
        return 'NO'

result = distinct_or_not()
print(result)