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 Java7 (OpenJDK 1.7.0) (judge verdict: Accepted)


import java.util.*;

public class Main{
    public static void main(String args[])
    {
    	boolean ans=true;
        Scanner sc=new Scanner(System.in);     
        int size=sc.nextInt();
        int elements[]=new int[ size];
        for(int i=0;i<size;i++)
        {
        	elements[i]=sc.nextInt();
        	   	
        }
        Arrays.sort(elements);
        for(int j=size-1;j>0;j--)
        {
        if(elements[j]==elements[j-1])
        {
        	ans=false;
        	break;
        }
        }
        
        if(ans)
       System.out.println("YES");
        else
        {
        	System.out.println("NO");
        	
        
        }
        
        sc.close();
        
    }
    
}