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: Wrong Answer)

import java.util.*;
import java.util.Collections;
import java.util.ArrayList;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        String[] A = new String[N];
        ArrayList<String> list = new ArrayList<String>();

        for(int i=0; i<N; i++){
            A[i] = sc.next();
            list.add(A[i]);
        }

        Collections.sort(list);
        System.out.println(list);

        for(int i=0 ; i<N-1; i++){
            if(list.get(i).equals(list.get(i+1))){
                System.out.println("NO");
                break;
            }
            if(i==N-2){
                System.out.println("YES");
            }
        }
    }
}