Striking slipper
One evening, Agafiya Petrivna walked into her kitchen and found a large group of cockroaches on the table. She quickly grabbed a slipper and started to eliminate them one by one. Her first attempt was not very successful, as she managed to kill only one cockroach. However, with her second strike, she improved slightly, killing two cockroaches. With each subsequent strike, she became more effective, with her k-th strike killing k times more cockroaches than the previous one. The task is to determine how many cockroaches Agafiya Petrivna managed to kill in total after delivering N strikes with the slipper.
Note: No cockroaches died from any other causes on that day.
Input
You are given a single natural number N (N ≤ 10).
Output
Output a single number, which is the total number of cockroaches killed.