#coding:utf-8
import sys,os
from collections import defaultdict, deque
from fractions import gcd
from math import ceil, floor
sys.setrecursionlimit(10**6)
write = sys.stdout.write
dbg = (lambda *something: print(*something)) if 'TERM_PROGRAM' in os.environ else lambda *x: 0
def main(given=sys.stdin.readline):
    input = lambda: given().rstrip()
    LMIIS = lambda: list(map(int,input().split()))
    II = lambda: int(input())
    XLMIIS = lambda x: [LMIIS() for _ in range(x)]
    YN = lambda c : print('Yes') if c else print('No')
    MOD = 10**9+7
    N = II()
    A = LMIIS()
    print('YES' if len(A) == len(set(A)) else 'NO')

    

if __name__ == '__main__':
    main() import sys,os sys os from collections import defaultdict, deque from fractions import gcd from math import ceil, floor sys.setrecursionlimit(10**6) sys.setrecursionlimit sys setrecursionlimit 10**6 10 6 write = sys.stdout.write write sys.stdout.write sys.stdout sys stdout write dbg = (lambda *something: print(*something)) if 'TERM_PROGRAM' in os.environ else lambda *x: 0 dbg (lambda *something: print(*something)) if 'TERM_PROGRAM' in os.environ else lambda *x: 0 'TERM_PROGRAM' in os.environ 'TERM_PROGRAM' os.environ os environ lambda *something: print(*something) print(*something) print *something something *something lambda *x: 0 0 *x def main(given=sys.stdin.readline):
    input = lambda: given().rstrip()
    LMIIS = lambda: list(map(int,input().split()))
    II = lambda: int(input())
    XLMIIS = lambda x: [LMIIS() for _ in range(x)]
    YN = lambda c : print('Yes') if c else print('No')
    MOD = 10**9+7
    N = II()
    A = LMIIS()
    print('YES' if len(A) == len(set(A)) else 'NO')

     main input = lambda: given().rstrip() input lambda: given().rstrip() given().rstrip() ().rstrip () given rstrip LMIIS = lambda: list(map(int,input().split())) LMIIS lambda: list(map(int,input().split())) list(map(int,input().split())) list map(int,input().split()) map int input().split() ().split () input split II = lambda: int(input()) II lambda: int(input()) int(input()) int input() input LMIIS() for _ in range(x) for _ in range(x) _ range(x) range x for _ in range(x) LMIIS() LMIIS XLMIIS = lambda x: [LMIIS() for _ in range(x)] XLMIIS lambda x: [LMIIS() for _ in range(x)] [LMIIS() for _ in range(x)] x YN = lambda c : print('Yes') if c else print('No') YN lambda c : print('Yes') if c else print('No') print('Yes') if c else print('No') c print('Yes') print 'Yes' print('No') print 'No' c MOD = 10**9+7 MOD 10**9+7 10**9 10 9 7 N = II() N II() II A = LMIIS() A LMIIS() LMIIS print('YES' if len(A) == len(set(A)) else 'NO') print 'YES' if len(A) == len(set(A)) else 'NO' len(A) == len(set(A)) len(A) len A len(set(A)) len set(A) set A 'YES' 'NO' given=sys.stdin.readline given sys.stdin.readline sys.stdin sys stdin readline if __name__ == '__main__':
    main() __name__ == '__main__' __name__ '__main__' main() main dbg = (lambda *something: print(*something)) if 'TERM_PROGRAM' in os.environ else lambda *x: 0 (lambda *something: print(*something)) if 'TERM_PROGRAM' in os.environ else lambda *x: 0 dbg def main(given=sys.stdin.readline):
    input = lambda: given().rstrip()
    LMIIS = lambda: list(map(int,input().split()))
    II = lambda: int(input())
    XLMIIS = lambda x: [LMIIS() for _ in range(x)]
    YN = lambda c : print('Yes') if c else print('No')
    MOD = 10**9+7
    N = II()
    A = LMIIS()
    print('YES' if len(A) == len(set(A)) else 'NO')

     def main(given=sys.stdin.readline):
    input = lambda: given().rstrip()
    LMIIS = lambda: list(map(int,input().split()))
    II = lambda: int(input())
    XLMIIS = lambda x: [LMIIS() for _ in range(x)]
    YN = lambda c : print('Yes') if c else print('No')
    MOD = 10**9+7
    N = II()
    A = LMIIS()
    print('YES' if len(A) == len(set(A)) else 'NO')

     main write = sys.stdout.write sys.stdout.write write
#coding:utf-8
import sys,os
from collections import defaultdict, deque
from fractions import gcd
from math import ceil, floor
sys.setrecursionlimit(10**6)
write = sys.stdout.write
dbg = (lambda *something: print(*something)) if 'TERM_PROGRAM' in os.environ else lambda *x: 0
def main(given=sys.stdin.readline):
    input = lambda: given().rstrip()
    LMIIS = lambda: list(map(int,input().split()))
    II = lambda: int(input())
    XLMIIS = lambda x: [LMIIS() for _ in range(x)]
    YN = lambda c : print('Yes') if c else print('No')
    MOD = 10**9+7
    N = II()
    A = LMIIS()
    print('YES' if len(A) == len(set(A)) else 'NO')

    

if __name__ == '__main__':
    main()