n=int(input())
a=[int(x) for x in input().split()]
if len(a) == len(set(a)):
    print("YES")
else:
    print("NO") n=int(input()) n int(input()) int input() input int(x) for x in input().split() for x in input().split() x input().split() ().split () input split for x in input().split() int(x) int x a=[int(x) for x in input().split()] a [int(x) for x in input().split()] if len(a) == len(set(a)):
    print("YES")
else:
    print("NO") len(a) == len(set(a)) len(a) len a len(set(a)) len set(a) set a print("YES") print "YES" print("NO") print "NO" a=[int(x) for x in input().split()] [int(x) for x in input().split()] a n=int(input()) int(input()) n
n=int(input())
a=[int(x) for x in input().split()]
if len(a) == len(set(a)):
    print("YES")
else:
    print("NO")