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>
 
int main() {
  int N;
  if (scanf("%d", &N) == 1) {
    N=N;
  };
  int A[N];
  for (int i = 0; i < N; i++) {
    if (scanf("%d", &(A[i])) == 1) {
 
      for (int j = 0; j < i; j++) {
	if (A[j] == A[i]) {
	  printf("NO\n");
	  return 0;
        }
      }        
    }
  }
 
  printf("YES\n");
  
  return 0;
}