import sys
N = int(next(sys.stdin))
A = tuple(map(int, next(sys.stdin).strip().split()))
a = frozenset(A)

print('YES' if len(A) == len(a) else 'NO') import sys sys N = int(next(sys.stdin)) N int(next(sys.stdin)) int next(sys.stdin) next sys.stdin sys stdin A = tuple(map(int, next(sys.stdin).strip().split())) A tuple(map(int, next(sys.stdin).strip().split())) tuple map(int, next(sys.stdin).strip().split()) map int next(sys.stdin).strip().split() (sys.stdin).strip().split (sys.stdin).strip() (sys.stdin).strip (sys.stdin) next sys.stdin sys stdin strip split a = frozenset(A) a frozenset(A) frozenset A print('YES' if len(A) == len(a) else 'NO') print 'YES' if len(A) == len(a) else 'NO' len(A) == len(a) len(A) len A len(a) len a 'YES' 'NO' N = int(next(sys.stdin)) int(next(sys.stdin)) N A = tuple(map(int, next(sys.stdin).strip().split())) tuple(map(int, next(sys.stdin).strip().split())) A a = frozenset(A) frozenset(A) a
import sys
N = int(next(sys.stdin))
A = tuple(map(int, next(sys.stdin).strip().split()))
a = frozenset(A)

print('YES' if len(A) == len(a) else 'NO')