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 (Clang 3.8.0) (judge verdict: Wrong Answer)

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

int comper(void *a, void *b)
{
	return (*(int *)a - *(int * )b);
}

int main(void)
{
	int n;
	scanf("%d", &n);

	int *a = malloc(n * sizeof(int));

	for (int i = 0; i < n; i++) {
		scanf("%d", a+i);
	}

	qsort(a, n, sizeof(int), comper);

	int i;

	for (i = 0; i < n - 1; i++) {
      if (bsearch(a+i, a+i+1, n-i-1, sizeof(int), comper)) {
        printf("NO %d\n", i);
        return 0;
      }
    }

  printf("YES\n");
	return 0;
}