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)

#include <stdio.h>
#include <stdlib.h>

int		is_distinct()
{
	int		N;
	int		nb;
	int		*nbrs;

	scanf("%d\n", &N);
	nbrs = (int *)malloc(sizeof(int) * (N + 1));
	for (int i = 0; i < N; i++)
	{
		scanf("%d\n", &nb);
		for (int n = 0; n < i; n++)
		{
			if (nbrs[n] == nb)
				return (0);
		}
		nbrs[i] = nb;
	}
	return (1);

}

int		main()
{
	int		r;

	r = is_distinct();
	if (r)
		printf("YES\n");
	else
		printf("NO\n");
	return (0);
}