#!/usr/bin/env python3

import sys

sys.setrecursionlimit(10000000)

INF = 1<<32



YES = "YES"  # type: str

NO = "NO"  # type: str



def solve(N: int, A: "List[int]"):

    from collections import Counter

    c = Counter(A)

    if len([k for k,v in list(c.items()) if v != 1]) == 0:

        print(YES)

    else:

        print(NO)

    return







def main():

    def iterate_tokens():

        for line in sys.stdin:

            for word in line.split():

                yield word

    tokens = iterate_tokens()

    N = int(next(tokens))  # type: int

    A = [int(next(tokens)) for _ in range(N)]  # type: "List[int]"

    solve(N, A)



if __name__ == '__main__':

    main()

#!/usr/bin/env python3

import sys

sys.setrecursionlimit(10000000)

INF = 1<<32



YES = "YES"  # type: str

NO = "NO"  # type: str



def solve(N: int, A: "List[int]"):

    if len(list(set(A))) == N:

        print(YES)

    else:

        print(NO)

    return







def main():

    def iterate_tokens():

        for line in sys.stdin:

            for word in line.split():

                yield word

    tokens = iterate_tokens()

    N = int(next(tokens))  # type: int

    A = [int(next(tokens)) for _ in range(N)]  # type: "List[int]"

    solve(N, A)



if __name__ == '__main__':

    main()

#!/usr/bin/env python3
import sys

sys.setrecursionlimit(10000000)
INF = 1 << 32
YES = "YES"  # type: str
NO = "NO"  # type: str


def solve(N: int, A: "List[int]"):
    from collections import Counter

    c = Counter(A)
    if len([k for k, v in list(c.items()) if v != 1]) == 0:
        print(YES)
    else:
        print(NO)
    return


def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word

    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    A = [int(next(tokens)) for _ in range(N)]  # type: "List[int]"
    solve(N, A)


if __name__ == "__main__":
    main()

#!/usr/bin/env python3
import sys

sys.setrecursionlimit(10000000)
INF = 1 << 32
YES = "YES"  # type: str
NO = "NO"  # type: str


def solve(N: int, A: "List[int]"):
    if len(list(set(A))) == N:
        print(YES)
    else:
        print(NO)
    return


def main():
    def iterate_tokens():
        for line in sys.stdin:
            for word in line.split():
                yield word

    tokens = iterate_tokens()
    N = int(next(tokens))  # type: int
    A = [int(next(tokens)) for _ in range(N)]  # type: "List[int]"
    solve(N, A)


if __name__ == "__main__":
    main()

-    from collections import Counter - -    c = Counter(A) -    if len([k for k, v in list(c.items()) if v != 1]) == 0: +    if len(list(set(A))) == N: