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 C++ (GCC 9.2.1) (judge verdict: Accepted)

#include<bits/stdc++.h>
#define Vsort(a) sort(a.begin(), a.end())
#define rep(i,n) for(int i = 0; i < (n); i++)
#define Srep(i,a,n) for(int i = (a); i < (n); i++)
using namespace std;

int main(){
  int n;
  bool ans=false;
  cin >> n;
  vector<int> a(n);
  rep(i,n) cin >> a[i];
  Vsort(a);
  rep(i,n-1) if(a[i] == a[i+1]) ans=true;
  ans ? cout << "NO" : cout << "YES";
}