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<string.h>
int main(){
  	int i,j,n,a[200000];
  	scanf("%d",&n);
  for(i = 0;i < n;i++)
  	scanf("%d",&a[i]);
	
  for(i = 1,j = 0;i < n;i++){         
      for(j = i - 1;j >= 0;j--){
           if(a[i] != a[j]){
              continue;
            }else{
              i = n + 1;
              break;
            }	
      }
  }
  
  	if(i == n){
      printf("YES\n");
    }else{
      printf("NO\n");
    }
    return 0;  	
}