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

        int number[] = new int[n];
        boolean res = false;
        for (int i = 0; i < n; i++) {
            number[i] = sc.nextInt();
        }
        point:for (int i = 0; i < number.length; i++) {
            for (int j = 0; j < number.length; j++) {
                if(i != j && number[i] == number[j]){
                    res = true;
                    System.out.println("NO");
                    break point;
                }
            }
        }
        if(!res)
            System.out.println("YES");
        sc.close();
    }
}