I can't count the number of duplicate in array

Question

//Write a program that will count total number of duplicate elements in array
import java.util.Scanner;
public class Yui{
public static void main(String [] args){
Scanner sc = new Scanner(System.in);
int [] elements = new int [3];
int dup = 0;
for(int ctr = 0; ctr <elements.length;ctr++){
System.out.print("Enter number of element: " );
elements[ctr] = sc.nextInt();
System.out.println("element " + " : " + elements[ctr]);
if(elements[ctr] == elements[ctr]){
dup += 1;
}
}
System.out.println("Total duplicate elements found in the array is: " + dup);
}
}
,