#!/bin/python3

import sys

def countArray(n, k, x):
    i=0
    sum=1
    sum1=1
    for i in range(1,k):
        sum=sum*i
    for i in range(1,k+1):
        sum1=sum1*i
    sum2=sum/sum1
    return sum+1


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)