import sys

N = int(sys.stdin.readline().rstrip())
A = [int(x) for x in sys.stdin.readline().rstrip().split()]

A.sort()

for i in range(N - 1):
    if A[i] == A[i + 1]:
        print("NO")
        break
else:
    print("YES") import sys sys N = int(sys.stdin.readline().rstrip()) N int(sys.stdin.readline().rstrip()) int sys.stdin.readline().rstrip() sys.stdin.readline().rstrip sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline rstrip int(x) for x in sys.stdin.readline().rstrip().split() for x in sys.stdin.readline().rstrip().split() x sys.stdin.readline().rstrip().split() sys.stdin.readline().rstrip().split sys.stdin.readline().rstrip() sys.stdin.readline().rstrip sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline rstrip split for x in sys.stdin.readline().rstrip().split() int(x) int x A = [int(x) for x in sys.stdin.readline().rstrip().split()] A [int(x) for x in sys.stdin.readline().rstrip().split()] A.sort() A.sort A sort for i in range(N - 1):
    if A[i] == A[i + 1]:
        print("NO")
        break
else:
    print("YES") i range(N - 1) range N - 1 N 1 if A[i] == A[i + 1]:
        print("NO")
        break A[i] == A[i + 1] A[i] A i A[i + 1] A i + 1 i 1 print("NO") print "NO" break print("YES") print "YES" A = [int(x) for x in sys.stdin.readline().rstrip().split()] [int(x) for x in sys.stdin.readline().rstrip().split()] A N = int(sys.stdin.readline().rstrip()) int(sys.stdin.readline().rstrip()) N
import sys

N = int(sys.stdin.readline().rstrip())
A = [int(x) for x in sys.stdin.readline().rstrip().split()]

A.sort()

for i in range(N - 1):
    if A[i] == A[i + 1]:
        print("NO")
        break
else:
    print("YES")
