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>
#include<vector>

using namespace std;

int main(void) {
	int H;
	cin >> H;
	vector<long long int>A(H);
	for (int i = 0; i < H; i++) {
		cin >> A[i];
	}
	bool issyo = true;
	for (int i = 0; i < H; i++) {
		for (int j = 1+i; j < H; j++) {
			if (A[i] == A[j]) {
				issyo = false;
				
			}
		}
	}
	if (issyo == false) {
		cout << "NO" << endl;
	}
	else {
		cout << "YES" << endl;
	}
}