#!/bin/python3

import sys
from math import factorial as fact
def countArray(n, k, x):
    C=fact(n)//(fact(k-1)*fact(n-(k-1)))
    return C//x
    # Return the number of ways to fill in the array.

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