Reverse Square Number Finding Program

import java.util.*;
import java.math.BigInteger;;
public class RevSqrNmbr {
   public static void main(String[] args) {
      Scanner sc = new Scanner(System.in);
      boolean bool = true;
      while(bool) {
         System.out.println("This program will count the number of _-digit reverse square numbers.");
         System.out.println("Enter number of digits:");
         int dig = sc.nextInt();
         while (dig < 1) {
            System.out.println("Invalid number of digits. Please enter a valid number.");
            dig = sc.nextInt();
         }
         int count = 0;
         for(BigInteger i = BigInteger.TEN.pow(dig - 1); i.compareTo(BigInteger.TEN.pow(dig)) < 0; i.add(BigInteger.ONE)) if(revSq(i)) {
            System.out.println(i.toString());
            count++;
         }
         System.out.println("There are " + count + " " + dig + "-digit reverse square numbers");
         System.out.println("Continue? Y or N");
         String str = sc.next();
         if(str.equalsIgnoreCase("n")) bool = false;
         else if(!str.equalsIgnoreCase("y")) {
            boolean cont = true;
            while (cont) {
               System.out.println("Invalid answer. Please enter a valid answer.");
               str = sc.next();
               if(str.equalsIgnoreCase("n")) cont = bool = false;
               else if(str.equalsIgnoreCase("y")) cont = false;
            }
         }
      }
   }

   public static boolean revSq(BigInteger i) {
      return rev(i.pow(2)) == rev(i).pow(2);
   }

   public static BigInteger rev(BigInteger i) {
      return new BigInteger(new StringBuilder(String.valueOf(i)).reverse().toString());
   }
}