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: Time Limit Exceeded)

#include <iostream>
using namespace std;
#define Nmax 200000

int main()
{
	int a[Nmax] = { 0 };
	int n;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}

	bool suc = true;
	for (int i = 0; i < n; i++) {
		for (int j = i + 1; j < n; j++) {
			if (a[i] == a[j]) {
				suc = false;
				break;
			}
		}
		if (!suc)
			break;
	}
	cout << (suc ? "YES" : "NO") << endl;

	return 0;
}