#!/bin/python3

import sys
import math
def nCr(n,r):
    f = math.factorial
    return int(f(n) / f(r) / f(n-r))

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