N,*A = map(int, open(0).read().split())
if len(set(A)) == len(A):
    print('YES')
else:
    print('NO') N,*A = map(int, open(0).read().split()) N map(int, open(0).read().split()) map int open(0).read().split() (0).read().split (0).read() (0).read (0) open 0 read split *A A if len(set(A)) == len(A):
    print('YES')
else:
    print('NO') len(set(A)) == len(A) len(set(A)) len set(A) set A len(A) len A print('YES') print 'YES' print('NO') print 'NO' N,*A = map(int, open(0).read().split()) map(int, open(0).read().split()) N
N,*A = map(int, open(0).read().split())
if len(set(A)) == len(A):
    print('YES')
else:
    print('NO')