Count, arrange

The thing is this--hdu has a network name called 8006 Male classmates, make countless friends, recently the classmate played a romantic, at the same time to n a Netizen each wrote a letter, this is nothing, it is, he unexpectedly put all the letters are loaded the wrong envelope! Watch out, it's all loaded wrong yo!

Now the question is: please help the poor 8006 students to calculate, altogether how many kinds of possible wrong way?

Input

The input data contains more than one test instance, one row per test instance, each row containing a positive integer n (1<n<=20), and N represents the number of 8006 netizens.

Output

For each line of input, output the number of possible error modes, and the output of each instance consumes one row.

Sample Input

23

Sample Output

12

#include <stdio.h>intMain () {intN,i; Long Longa[ A]; a[2]=1; a[3]=2;  for(i=4; i<= +; i++) A[i]= (I-1) * (a[i-1]+a[i-2]);  while(SCANF ("%d", &n)! =EOF) printf ("%lld\n", A[n]);return 0;}

Count, arrange