Use of Inheritance in Java

import java.io.*;
class acc
{
    static float bal=0.0f;
 
    void dep(float a)
    {
        bal=bal+a;
        balance();
    }

    void wdraw(float a)
    {
        if(a<=bal)
        bal=bal-a;
        else
        System.out.println("Not enough balance in ur account");
        balance();
    }

    void balance()
    {
        System.out.println("The current balance in ur account is: "+bal);
    }
}
  
class main_acc
{

    public static void main(String arg[])
    {

        int ch=0,z=0;
        float a=0.0f;
        acc a1=new acc();
        DataInputStream ins=new DataInputStream(System.in);
 

        System.out.println("1:Deposit");
        System.out.println("2:Withdraw");
    do
    {

        try
    {   

        System.out.println("Enter ur choice ");
        ch=Integer.parseInt(ins.readLine());
    }
    catch(IOException e)
    { }

    try
    {

        if(ch==1)
        {
            System.out.print("Enter how much money u want to deposit ");
            a=Integer.parseInt(ins.readLine());
            a1.dep(a);
        }
        else if(ch==2)
        {

            System.out.print("Enter how much money u want to withdraw ");
            a=Integer.parseInt(ins.readLine());
            a1.wdraw(a);
        }
        else
        System.out.println("Not a valid choice");
        System.out.println("Press 0 if u want another transaction ");
        z=Integer.parseInt(ins.readLine());
    }
    catch(IOException e)
    { }
    } while(z==0);
    }
}