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(void){
  int n;
  int s[200000];
  int f=0;
  scanf("%d",&n);
  for(int i=0; i<n; i++){
    scanf("%d",&s[i]);
    for(int j=i-1; j>=0; j--){
      if(s[j]==s[i]){
        f=1;
        break;
      }
    } 
  }
 
  if(f==0){
    printf("YES");
  }else{
    printf("NO");
  }
}