#!/bin/python3

import sys
def f(g) :
    if g == 1 :
        return 1
    else :
        return g*f(g-1)
def countArray(n, k, x):
    # Return the number of ways to fill in the array.
    t  = n-2
    fact = f(k)//f(k-t)
    sets  = fact//t
    sum = 0
    for i in range(2,sets+1) :
        if i != x :
            sum += t
        else :
            sum += (t-1)
    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)