def main():
    n = int(input())
    a = set(map(int, input().split(" ")))
    print("YES" if len(a) == n else "NO")

main() def main():
    n = int(input())
    a = set(map(int, input().split(" ")))
    print("YES" if len(a) == n else "NO") main n = int(input()) n int(input()) int input() input a = set(map(int, input().split(" "))) a set(map(int, input().split(" "))) set map(int, input().split(" ")) map int input().split(" ") ().split () input split " " print("YES" if len(a) == n else "NO") print "YES" if len(a) == n else "NO" len(a) == n len(a) len a n "YES" "NO" main() main def main():
    n = int(input())
    a = set(map(int, input().split(" ")))
    print("YES" if len(a) == n else "NO") def main():
    n = int(input())
    a = set(map(int, input().split(" ")))
    print("YES" if len(a) == n else "NO") main
def main():
    n = int(input())
    a = set(map(int, input().split(" ")))
    print("YES" if len(a) == n else "NO")

main()