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: Runtime Error)

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

int int_sort( const void *a , const void *b ) {
  if( *(int*)a < *(int*)b ) {
    return -1;
  }
  else
  if( *(int*)a == *(int*)b ) {
    return 0;
  }
  return 1;
}

int main(){
  int n,i,j,tmp,flag=0;
  int *a;
  
  scanf("%d",&n);
  a=(int*)malloc(sizeof(int));
  for(i=0;i<n;i++){
    scanf("%d",&a[i]);
  }
  
  qsort((void*)a ,n, sizeof(a[0]),int_sort);
  
  for(i=0;i<n;i++){
    if(i==0){
      tmp=a[0];
    }
    
    if(tmp!=a[i] && i!=0){
      tmp=a[i];
    } else {
      flag=1;
      break;
    }
  }
  
  if(flag==0){
    printf("YES");
  } else {
    printf("NO");
  }
}