#include <bits/stdc++.h>
using namespace std;
int dp[22][11][11][5][2];
int main() {
  int n, t;
  cin >> n >> t;
  if (n == 1) {
    cout << 0 << endl;
    return 0;
  }
  int i, j, k, l, h, x, y;
  dp[2][0][0][1][0] = 3;
  dp[2][0][0][1][1] = 0;
  dp[2][0][0][2][0] = 2;
  dp[2][0][0][2][1] = 1;
  dp[2][0][0][3][0] = 1;
  dp[2][0][0][3][1] = 2;
  dp[2][0][0][4][0] = 0;
  dp[2][0][0][4][1] = 3;
  for (i = 3; i <= n; i++)
    for (j = t; j >= 0; j--)
      for (k = t - 1; k >= 0; k--) {
        for (x = 1; x <= 4; x++) {
          for (y = 1; y < x; y++) {
            if (k > 0) dp[i][j][k][x][1] += dp[i - 1][j][k - 1][y][0];
            dp[i][j][k][x][1] += dp[i - 1][j][k][y][1];
          }
          for (y = x + 1; y <= 4; y++) {
            if (j > 0) dp[i][j][k][x][0] += dp[i - 1][j - 1][k][y][1];
            dp[i][j][k][x][0] += dp[i - 1][j][k][y][0];
          }
        }
      }
  int rinka = 0;
  for (i = 1; i <= 4; i++)
    for (j = 0; j <= 1; j++) rinka += dp[n][t][t - 1][i][j];
  cout << rinka << endl;
  return 0;
}
