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>
#include <stdlib.h>
int main ( void ){
  int n;
  int *a;
  int hoge,piyo;
  int flag;
  flag = 0;
  scanf ("%d",&n);
  a = malloc ( n * sizeof ( int ));
  for ( hoge = 0 ; hoge < n ; hoge++ ){
    scanf ("%d",&a[hoge]);
    for ( piyo = 0 ; piyo < hoge ; piyo++ ){
      if ( a[hoge] == a[piyo] ) flag = 1;
      else flag = 0;
    }
  }
  if ( flag != 0 ) printf("YES");
  else printf("NO");

  return 0;
}