#!/usr/bin/php
<?php

/*  Canadian Computing Competition


   Example program to demonstrate input and output and time limit.


   Programming Language:  PHP 5.0.3


   Specification:


      Write a program that reads several positive integers, one per
      line.  For each integer n, output the number of orderings
      possible for a set of n distinct values.  n will not exceed 11.
      The last line of input is indicated with n being 0.


   Sample Input:


      1
      11
      0


   Output for Sample Input:


      1
      39916800


   Implementation:

      The answer is n! (n factorial) which is easily computed in n steps.
      But this program does it the hard way.  It uses a recursive function
      to enumerate and count all the possible orderings.


   How to run the program:

      The program reads from "standard input" and writes to "standard output."
      Run the program as:
        ./factorial.php < input.txt
      or, if you wish to just type numbers at the program, run by
        ./factorial.php

   Run-time:

      Please time the execution time of this program on your computer,
      using the sample input.  This time is the maximum that should be
      allowed for any CCC program.

      On a 1.8 GHz processor, this program runs in about 1.32ms (milliseconds).
      (Your results will vary depending on processor, compiler, and
      compiler options.)

   Limitations:

      - Cannot (at the moment) spit answers as input is entered. This is
        a trivial addition.
      - Input taking is stopped if input is 0. But 0! = 1.
      - Factorials of negative integers is undefined. The program outputs 1.

   Written by:

      Rajesh Kumar <rks@meetrajesh.com>

*/

/* Uses PEAR::Benchmark to time program execution 
   Available from http://pear.php.net/package/Benchmark */

error_reporting(E_ALL);
require 'Benchmark/Timer.php';

$timer = new Benchmark_Timer(TRUE);
$timer->setMarker('Mark1');

while (1) {

    $x = rtrim(fgets(STDIN));

    if (empty($x)) {
        break ;
    } else {
        $input[] = $x;
    }

}

$timer->setMarker('Mark2');

foreach ((array) $input as $val) {

    if ($val == 0) {
        break;
    }

    fputs(STDOUT, factorial($val) . "\n");

}

$timer->setMarker('Mark3');

function factorial($int) {

    $res = 1;
    $int = intval($int);

    while ($int > 0 && $int <= 11) {

        $res *= $int;
        $int--;

    }

    return $res;

}

$timer->stop();
fputs(STDOUT, "\n");

?>