import java.util.Scanner;

/*
Factorial program
 */
public class main {
    public static void testing(String[] args){
        System.out.println("This program is using \"for\" loop.\n");
        Scanner myObj = new Scanner(System.in);
        System.out.println("Enter number from 0 to 20.\n");
        int num = myObj.nextInt(), result=1;

        if(num<0 || num>20){
            System.out.println("Wrong number!\nTry again!");
            testing(null);
        }
        else {
            for (int i = 1, j = num; j > 0; j = j - 1, i = i + 1) {
                System.out.println(j);
                System.out.println(i);
                result = result * i;
            }
        }
        System.out.println("Factorial of: (" + num + "!) is equal to "+ result);
    }
}