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.Scanner;
public class Main{
    public static void main(String[]args){
        Scanner scan = new Scanner(System.in);
        int n,flag;
        flag=0;
        n= scan.nextInt();
        int[] arr = new int[n];
        for(int i=0;i<n;i++){
            arr[i] = scan.nextInt();
        }
        for(int i=0;i<n-1;i++){
            for(int j=i+1;j<n;j++){
                if(arr[i]==arr[j]){
                    flag=1;
                    System.out.printf("NO");
                    break;
                }
            }
            if(flag==1) break;
        }
        if(flag==0) System.out.printf("YES");
    }
}