#!/bin/python3

import sys
import math

def countArray(n, k, x):
    sum=int(0);
    # Return the number of ways to fill in the array.
    num=math.factorial(k);
    m=math.factorial(n-2);
    l=math.factorial(k-(n-2));
    den=m*l;
    sum=int(num/den);
    return sum;

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)