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 rmElements = k - 1;
        if(k >=x){
            rmElements = k - 1;
        }
        int numberOfWays = (int)((factorial(k))/ (factorial((k-(n-2)))));
        return (numberOfWays-3);    
    }
    
    static long factorial(int n){
        if(n == 1) {
            return 1;
        }
        return n*factorial(n-1);    
    }

    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();
    }
}