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) {
        n = n-2;
        int[] fact = new int[Math.max(n,k)+1];
        fact[1] = 1;
        for(int i = 2; i<=Math.max(n,k); i++) fact[i] = fact[i-1]*i;
        return fact[k]/(fact[n]*fact[k-n]);
    }

    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();
    }
}