/*

     Name:nyoj-451-光棍节的快乐

     Copyright:

     Author:

     Date: 2018/4/25 16:44:47

     Description:D(n)=(n-1)*(D(n-1)*D(n-2))[D[0]=0;D[1]=1]

 */

 #include <iostream>

 #include <cstdio>

 using namespace std;

 long long c[][], wrongsort[];

 int main()

 {

     for (int i=; i<=; i++) {//阶乘打表

         c[i][] = c[i][i] = ;

         for (int j=; j<i; j++) {

             c[i][j] = c[i-][j] + c[i-][j-];

         }

     }

     wrongsort[] = ;

     wrongsort[] = ;

     for (int i=; i<=; i++) {//错排打表

         wrongsort[i] = (i-) * (wrongsort[i-] + wrongsort[i-]);

     }

     int n,m;

     while (cin>>n>>m) {

         cout<<c[n][n-m]*wrongsort[m]<<endl;

     }

     return ;

 }