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.*;
public class Main{
	public static void main(String[] args){
    	Scanner sc=new Scanner(System.in);
    	int n=sc.nextInt();
    	int[] x=new int[n];
    	boolean can = true;
    	for(int i=0;i<n;i++)
    		x[i] = sc.nextInt();
    	Arrays.sort(x);
    	for(int i=0;i<n-1;i++) {
    		if(x[i]==x[i+1]) {
    			can = false;
    				break;
    		}
    	}
    	String s = can?"YES":"NO";
    	System.out.println(s);
	}
}