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 5.4.1) (judge verdict: Time Limit Exceeded)

#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <limits.h>

int main(void)
{
	int nums[200000] = {};
	int index = 0;

	scanf("%d", &index);
	if (2 <= index && index <= 200000)
	{
		int tmp = 0;
		for (int i = 0; i < index; i++)
		{
			scanf("%d", &tmp);
			for (int j = 0; j < i; j++)
			{
				if (tmp == nums[j])
				{
					printf("NO\n");
					return 0;
				}
			}
			nums[i] = tmp;
			tmp = 0;
		}
		printf("YES\n");
		return 0;
	}	
	printf("NO\n");
	return 0;
}