An Efficient Kaprekar Number

import java.io.*; 
class karpekar //sum of digits in its square is the number itself e.g., 45 
{ 
public static void main()throws IOException 
{ 
    BufferedReader br=new BufferedReader(new InputStreamReader(System.in)); 
    System.out.println("Enter a number"); 
    int num=Integer.parseInt(br.readLine()); 
    int n=num; 
    int sq=num*num; 
    int count=0; 
    while(n!=0) 
    { 
      n=n/10; 
      count++; 
     } 
     int sq1=(int)(sq/Math.pow(10,count)); 
     int sq2=(int)(sq%Math.pow(10,count)); 
     if(sq1+sq2==num) 
     { 
        System.out.println("It is a karpekar number"); 
     } 
     else 
     { 
        System.out.println("It is not a karpekar number"); 
      } 
   } 
}