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: Accepted)

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
public class Main{
	public static void main(String[]args) {
		Scanner sc=new Scanner(System.in);
	    int n=sc.nextInt();
	    boolean b=true;
	    int[]arr=new int[n];
	    for(int i=0;i<n;i++) {
	    	arr[i]=sc.nextInt();
	    }
	    Arrays.sort(arr);
	    for(int i=0;i<n-1;i++) {
	    	if(arr[i]==arr[i+1]) {
	    		b=false;
	    		break;
	    	}
	    }
	    if(b==true)
	    	System.out.println("YES");
	    else
	    	System.out.println("NO");
	}
	
}