#!/bin/python3

import sys
def fact(x):
    j=1
    for i in range(1,(x+1)):
        j=j*i
    return j 
def countArray(n, k, x):
    l=[]
    l[0]=1
    l[n-1]=x
    l1=[]
    for i in range(2,(k+1)):
        if(i!=x):
            l1.append(i)
    s=set(l1)
    
    remspace=n-3
    remele=len(l1)
    w=fact(remele)//fact(remele-remspace)
    s1=s-{x}
    l1=list(s1)
    s.add(1)
    for i in l1:
        s2=s-{i}-{1}
        l3=list(s2)
        remspace=n-3
        remele=len(l2)
        w1=fact(remele)//fact(remele-remspace)
    w3=w+w1
    return w3
        
     
            
            

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)