Problem:
Score : 300 points

Problem Statement

Given is a sequence of integers A_1, A_2, ..., A_N.
If its elements are pairwise distinct, print YES; otherwise, print NO.

Constraints

2 ≤ N ≤ 200000

1 ≤ A_i ≤ 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 ... A_N

Output

If the elements of the sequence are pairwise distinct, print YES; otherwise, print NO.

Sample Input 1

5
2 6 1 4 5

Sample Output 1

YES

The elements are pairwise distinct.

Sample Input 2

6
4 1 3 1 6 2

Sample Output 2

NO

The second and fourth elements are identical.

Sample Input 3

2
10000000 10000000

Sample Output 3

NO

Solution in PyPy3 (2.4.0) (judge verdict: Wrong Answer)

N=int(input())
s=list(map(int,input().split()))
# N=6
# s=[4 ,1 ,3 ,1 ,6 ,2]


from collections import Counter
S=Counter(s)#カウンタークラスが作られる。S=Counter({'b': 5, 'c': 4, 'a': 3})

if S.most_common(1)[0][1]==1:
    print("YES")
else:
    print("N0")