// Recursive factorial in Java

public class Factorial {
  public static void main(String[] args) {
    int n = Integer.parseInt(args[0]);
    System.out.println(fac(n));
  }
  
  static int fac(int n) {
    if (n == 0)
      return 1;
    else 
      return n * fac(n-1);
  }
}