import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


n = int(input())
a = list(map(int, input().split()))
if len(a)==len(set(a)):
    print("YES")
else:
    print("NO") import sys sys input = lambda : sys.stdin.readline().rstrip() input lambda : sys.stdin.readline().rstrip() sys.stdin.readline().rstrip() sys.stdin.readline().rstrip sys.stdin.readline() sys.stdin.readline sys.stdin sys stdin readline rstrip sys.setrecursionlimit(max(1000, 10**9)) sys.setrecursionlimit sys setrecursionlimit max(1000, 10**9) max 1000 10**9 10 9 write = lambda x: sys.stdout.write(x+"\n") write lambda x: sys.stdout.write(x+"\n") sys.stdout.write(x+"\n") sys.stdout.write sys.stdout sys stdout write x+"\n" x "\n" x n = int(input()) n int(input()) int input() input a = list(map(int, input().split())) a list(map(int, input().split())) list map(int, input().split()) map int input().split() ().split () 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" input = lambda : sys.stdin.readline().rstrip() lambda : sys.stdin.readline().rstrip() input write = lambda x: sys.stdout.write(x+"\n") lambda x: sys.stdout.write(x+"\n") write n = int(input()) int(input()) n a = list(map(int, input().split())) list(map(int, input().split())) a
import sys
input = lambda : sys.stdin.readline().rstrip()
sys.setrecursionlimit(max(1000, 10**9))
write = lambda x: sys.stdout.write(x+"\n")


n = int(input())
a = list(map(int, input().split()))
if len(a)==len(set(a)):
    print("YES")
else:
    print("NO")