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 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#define rep(i, n)   for(i = 0; i < (int)(n); i++)
typedef long long ll;

int compare_ll(const void *a, const void *b){
  return *(ll*)a - *(ll*)b;
}

int main(){
  ll  i, n, a[200000+1] = {0};
  scanf("%lld", &n);
  rep(n,i){ scanf("%lld", &a[i]); }
  qsort( a, n, sizeof(ll), compare_ll );
  
  rep(i,n-1){
    if( a[i] == a[i+1] ){ printf("NO\n"); return 0; }
  }
  printf("YES\n");
  return 0;
}