#include <bits/stdc++.h>
using namespace std;
const int MAXN = 20, MAXT = 10, MAXK = 4, MAXR = 2;
int n, t, f[MAXN + 2][MAXK + 2][MAXT + 2][MAXR + 2];
int Ans;
int main() {
  scanf("%d%d", &n, &t);
  f[2][2][1][1] = 1;
  f[2][3][1][1] = 2;
  f[2][4][1][1] = 3;
  for (int i = 3; i <= n; i++)
    for (int j = 1; j <= 4; j++)
      for (int k = 1; k <= t; k++) {
        for (int r = 4; r > j; r--)
          f[i][j][k][0] += f[i - 1][r][k][0] + f[i - 1][r][k][1];
        for (int r = 1; r < j; r++)
          f[i][j][k][1] += f[i - 1][r][k][1] + f[i - 1][r][k - 1][0];
      }
  for (int i = 1; i <= MAXK; i++) Ans += f[n][i][t][0];
  printf("%d\n", Ans);
  return 0;
}
