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 Java (OpenJDK 11.0.6) (judge verdict: Accepted)

import java.util.*;

public class Main{

	public static void main(String[] args){

		Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        int[] a = new int[N];
        //ArrayList<Integer> A = new ArrayList<>();
       
        for(int i = 0; i < N; i++){
          a[i] = sc.nextInt();
        }
        
       Arrays.sort(a);
       for(int i = 1; i < N; i++){
         if(a[i] == a[i-1]){
           System.out.println("NO");
           return;
         }else{

         }
       }
       
       System.out.println("YES");
      
	}

}