n=int(input())
a=list(map(int,input().split()))
a=sorted(a)
f=0
for i in range(n-1):
    if a[i]==a[i+1]:
        f=1
print("YES" if f==0 else "NO")
    
    
        
        
    
    
    
    
         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 a=sorted(a) a sorted(a) sorted a f=0 f 0 for i in range(n-1):
    if a[i]==a[i+1]:
        f=1 i range(n-1) range n-1 n 1 if a[i]==a[i+1]:
        f=1 a[i]==a[i+1] a[i] a i a[i+1] a i+1 i 1 f=1 f 1 print("YES" if f==0 else "NO") print "YES" if f==0 else "NO" f==0 f 0 "YES" "NO" f=0 0 f a=list(map(int,input().split())) list(map(int,input().split())) a n=int(input()) int(input()) n f=1 1 f a=sorted(a) sorted(a) a
n=int(input())
a=list(map(int,input().split()))
a=sorted(a)
f=0
for i in range(n-1):
    if a[i]==a[i+1]:
        f=1
print("YES" if f==0 else "NO")
    
    
        
        
    
    
    
    
        
