Children are always sweet but they can sometimes
make you feel bitter. In this problem, you will see how Tintin, a five year’s
old boy, creates trouble for his parents. Tintin is a joyful boy and is always
busy in doing something. But what he does is not always pleasant for his
parents. He likes most to play with household things like his father’s
wristwatch or his mother’s comb. After his playing he places it in some other
place. Tintin is very intelligent and a boy with a very sharp memory. To make
things worse for his parents, he never returns the things he has taken for
playing to their original places.
Think about a morning when Tintin has managed to ‘steal’ three household objects. Now, in how many ways he can place those things such that nothing is placed in their original place. Tintin does not like to give his parents that much trouble. So, he does not leave anything in a completely new place; he merely permutes the objects.
There will be several test cases. Each will have a positive integer less than or equal to 800 indicating the number of things Tintin has taken for playing. Each integer will be in a line by itself. The input is terminated by a –1 (minus one) in a single line, which should not be processed.
For each test case print an integer indicating in how many ways Tintin can rearrange the things he has taken.
2
3
4
-1
1
2
9
Problemsetter: Tanveer Ahsan (Idea from Shamsul Alam)