#!/bin/python
from math import factorial
import sys

def countArray(n, k, x):
    return factorial(k)-3
    
    

if __name__ == "__main__":
    n, k, x = raw_input().strip().split(' ')
    n, k, x = [int(n), int(k), int(x)]
    answer = countArray(n, k, x)
    print answer