import java.util.Scanner;
import java.util.*;

public class BinaryToDecimal {
  public static void main(String[] args) {
  Scanner in = new Scanner(System.in);
    System.out.println("Please enter either a binary number as a sequence of 1's and 0's or type 'quit' to exit the program");
  String bin = in.nextLine();
  String bin2 = bin.toLowerCase();
  int len = bin2.length();


 if (bin2.indexOf("quit") > -1 && len == 4){
   return;}

 while (bin2.indexOf("quit") > -1 && len != 4)
 {System.out.println("Input can't have letters besides specifically entering the word 'quit' to exit the program");
  bin2 = in.nextLine();}

while (bin2.indexOf("quit") == -1){
  if (bin2.matches("\\d[01]+")){System.out.println("Testing testing 123");}
  else if (!bin2.matches("\\d[01]+")) {
  System.out.println("Input can't have numbers besides 1 and 0, or any letters if you have not decided to exit with the 'quit' command");
  bin2 = in.nextLine();}
  }
  }
  }