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 Java8 (OpenJDK 1.8.0) (judge verdict: Time Limit Exceeded)

import java.util.*;
import java.util.Comparator;
 
public class Main { 
    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);       
        int n=sc.nextInt();
        String o="YES";
        int[] a=new int[n];
        for(int i=0;i<n;i++){
        	a[i]=sc.nextInt();
            for(int j=0;j<i;j++){
            	if(a[j]==a[i]){
                	o="NO";
                    System.out.println(o);
                    return;
                }
            }
        }
      System.out.println(o);
    }
}