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.Scanner;
import java.util.Arrays;

public class Main{
  public static void main(String[] args){
    Scanner scanner = new Scanner(System.in);
    
    int N = scanner.nextInt();
    int A[] = new int[N];
    for(int i = 0;i < N;i++){
      A[i] = scanner.nextInt();
    }
    Arrays.sort(A);
    String answer = "Yes";
    for(int i = 0;i < N - 1;i++){
      if(A[i] == A[i + 1]) answer = "No";
    }
    System.out.println(answer);
  }
}