import javax.swing.JOptionPane;
public class mainclass {
 public static void main(String[] args) {
  String number;
  int result,inputNumber;
  number = JOptionPane.showInputDialog("enter a number");
  inputNumber = Integer.parseInt(number);
  result = computeFactorial(inputNumber);
  JOptionPane.showMessageDialog(null, "the factorial is :" + result);
 }
 public static int computeFactorial(int n) {
  int i;
  int result = 1;
  for (i = 1; i <= n; i++){
   result = result * i;
  }
  return result;
 }
}