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<iostream>
#include<iomanip>
#include<string>
#include<array>
#include<cmath>
#include<vector>
#include<utility>
#include<algorithm>
#include<ctype.h>
using namespace std;


int main() {
	int a[200010],n;
	cin >> n;
	for (int i = 0; i < n;i++) {
		cin >> a[i];
	}
	sort(a,a+n);
	for (int i = 0; i < n - 1;i++) {
		if (a[i]==a[i+1]) {
			cout << "NO" << endl;
			return 0;
		}
	}
	cout << "YES" << endl;
}