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: Wrong Answer)

import java.util.*;

public class Main {
 
  public static void main(String[] args) {
    
    Scanner sc = new Scanner(System.in);
    
    List<Integer> list = new ArrayList<Integer>();
    while(sc.hasNext()) {
      list.add(sc.nextInt());
    }
    
    boolean distinct = true;
    for (int i = list.size() - 1; i > 0; i--) {
      int a = list.remove(i);
      if (list.indexOf(a) >= 0) {
        distinct = false;
        break;
      } else {
        continue;
      }
    }
    
    if (distinct) {System.out.println("Yes");} else {System.out.println("No");}
    
  }
  
}