#include <iostream>
#include <algorithm>
#include <vector>
#include <cstdio>
using namespace std;

int main(void){
	int n, k; cin >> n >> k;
	vector<int> v;
	v.push_back(k);
	for (int i = 1; i <= n; ++i){
		if(i != k) v.push_back(i);
	}
	int sum = 0;
	do{
		if(v[0] != k) break;
		/*
		for (int i = 0; i < v.size(); ++i){
			printf("%d ", v[i]);
		}
		printf("\n");
		*/
		int flag = 0;
		for (int i = 0; i < v.size() - 1; ++i){
			if(v[i] > v[i + 1]){
				flag++;
			}
		}
		if(flag == 1) sum++;
	}while(next_permutation(v.begin(), v.end()));

	printf("%d\n", sum);
	return 0;
}