nested class java

import java.util.Scanner;



class lesson1{
 public static void main(String[] args) {
     int a,b,c;
     System.out.println("enter two integer");
     Scanner sn = new Scanner(System.in);
     a= sn.nextInt();
     b= sn.nextInt();
     c=a+b;
    System.out.println("the sum of the two given integer is: "+c);

      prime();
     salary();
    factorial();
    weird();
    pali();12
     Avagdrow();
    calculator();
 }


public static void prime()///////CODE FOR PRIME NUMBERS//////////
{
    int n;
    Scanner ss = new Scanner(System.in);
    System.out.println("enter a integer to know if it is prime number or not ");
    n =ss.nextInt();
    if (n%2==0) {
        System.out.println("the integer is prime ");
    } else {
        System.out.println("the Interger is !prime ");
    }

}


public  static void salary()/////////CODE FOR BASIC SALARY //////////
{
    double sal;
    double epf,hra,da,ta,netsal;
    System.out.println("enter your current salary");
    Scanner sc = new Scanner(System.in);
    sal=sc.nextDouble();
    hra=(sal*100/10);
    epf=(sal*100/25);
    ta=(sal*100/50);
    da=(sal*100/12);
    netsal=(hra+ta-da+epf);
    System.out.println("the net salary is:"+netsal);


}
                 ////////////CODE FOR FACTORIAL OF A NUMBER///////////
/public static void factorial()
{
int n,i;
int fac = 1;
Scanner sn =new Scanner(System.in);
System.out.println("enter a integer for Factorial");
n=sn.nextInt();
for(i=1 ;i<=n; ++i)
{
    fac*=i;

}
System.out.println("factorial:  "+fac);
}
           /////////////CODE FOR TWISTING DIGITS OF THE NUMBER///////////
public static void weird()
{
    int num,rem;
    int e=0 , o=0;
    Scanner scc = new Scanner(System.in);
    System.out.println("Enter an integer ");
    num = scc.nextInt();
    while(num>0){
            rem=num%10;
            if(rem%2==0)
            {
                e++;
            }
            else{
                o++;
            }
            num=num/10;

    }

    System.out.println("H"+e  +o);


}

            //////CODE FOR PALINDROME NUMBER///////////////
public static void pali()
{
    int num,rem,k=0;
     System.out.println("enter an integer");
    Scanner scc = new Scanner(System.in);
    num=scc.nextInt();
    int y =  num;
    while(num>0){
        rem =num %10;
        num =num /10;
        k = (k *10)+rem;

    }
    if (k==y) {
        System.out.println("the  is palindrome");
    } else {
        System.out.println("the is ! palindrome");
    }

}

public static void Avagdrow()////CODE FOR AVAGADROW NUMBER/////////
{
    int num,k,rem,A=0;
    Scanner scc = new Scanner(System.in);
    System.out.println("Enter an interger ");
    num=scc.nextInt();
    int y = num;
    while(num>0)
    {
        rem=num%10;
        num=num/10;
        A=(rem*rem*rem)+A;
    }
    if (A==y) {
        System.out.println("this is a Avagadrow number");
    } else {
        System.out.println("this ! a Avagadrow number");
    }
}


public static long calculator()///////CODE FOR THE CALCULATOR //////////
{

         int num1, num2, choice;

        Scanner sc = new Scanner(System.in);
        boolean check = false;
         do{

           System.out.println("Enter two integers: ");

           num1 = sc.nextInt();
           num2 = sc.nextInt();
           System.out.println("1: Addition");
           System.out.println("2: Subtract");
           System.out.println("4: Divide");
           System.out.println("0: Quit");
           System.out.println("Enter Choice: ");
          choice = sc.nextInt();
           if (choice == 1){

            System.out.println(num1 + num2);

           }else if (choice == 2){

             System.out.println(num1 - num2);

           }else if (choice == 3){

             System.out.println(num1 * num2);

           }else if (choice == 4){

             System.out.println(num1 / num2);

           }else if (choice == 0)
            {

             System.out.println("This way to the exit.");

             System.exit(0);

            }else
                {

             System.out.println("Error, entered wrong number.");
           }

      while (check==true);

       System.out.print("Finished.");

      }while (choice >= 5);
return 0;
     }

     }