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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
using namespace std;

int main() {
	int n,m,i,j,k,ans,cur;
	cin >> n;
	vector<int> a(n);
	
	for(i=0; i<n; i++){
		cin >> a[i];
	}
	sort(a.begin(),a.end());
	ans=0;
	for(i=0; i<n-1; i++){
		if(a[i]==a[i+1]){
			ans++;
		}
	}
	if(ans==0){
		cout << "YES";
	}else{
		cout << "NO";
	}
}