import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    static long countArray(int n, int k, int x) {
        // Return the number of ways to fill in the array.
        int pos=n-2;
        int fact=factorial(k,pos);
        int fact1=factorial(k-1, k-2);
        return (fact-(fact1+fact1)+1);
    }
    static int  factorial(int k,int pos){
        int num=facto(k);
        int den=facto(k-pos);
        return (num/den);
    }
        static int facto(int n){
             int res=1;
           for(int i=n;i>1;i--){
            res*=i;
              }
        
        return res;   
        }
       
    

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int k = in.nextInt();
        int x = in.nextInt();
        long answer = countArray(n, k, x);
        System.out.println(answer);
        in.close();
    }
}