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>
#include<stdlib.h>

int main(void){
  int N,i,j,tmp;
  int a[200008];
  scanf("%d\n",&N );
  for(i=0; i<N; i++){
    scanf("%d",&a[i] );
  }
  for(i=0; i<N; i++){
    for(j = i+1; j<N; j++){
      if(a[i] > a[j]){
        tmp = a[i];
        a[i] = a[j];
        a[j] = tmp;
      }
    }
    if((a[i] == a[i-1])&&(i>0)){
      printf("NO" );
      exit(0);
    }
  }
  printf("YES" );
  return 0;
}