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: Wrong Answer)

#include <stdio.h>

int main(void)
{
  long n;
  scanf("%ld", &n);
  long long a[n];
  int ans = 0;

  for (long i = 0; i < n; i++)
    scanf("%lld", &a[i]);

  for (long i = 0; i < n; i++) {
    for (long j = i + 1; j < n; j++) {
      if (a[i] == a[j]) {
	ans++;
      break;
      }
    }
  }
  if (ans) printf("No\n");
  else printf("Yes\n");

  return 0;
}