#include <bits/stdc++.h>
using namespace std;
long long dp[22][12][12][5][5];
int main() {
  int n, t;
  cin >> n >> t;
  for (int a = 1; a < 5; ++a) {
    for (int b = 1; b < 5; ++b) {
      if (a != b) {
        dp[2][0][0][a][b] = 1;
      }
    }
  }
  for (int i = 2; i < n; ++i) {
    for (int k = 0; k <= t; ++k)
      for (int l = 0; l <= t - 1; ++l) {
        for (int a = 1; a < 5; ++a) {
          for (int b = 1; b < 5; ++b) {
            if (a == b) {
              continue;
            }
            for (int c = 1; c < 5; ++c) {
              if (c == b) {
                continue;
              }
              if (a > b && b < c) {
                dp[i + 1][k][l + 1][b][c] += dp[i][k][l][a][b];
              } else if (a < b && b > c) {
                dp[i + 1][k + 1][l][b][c] += dp[i][k][l][a][b];
              } else {
                dp[i + 1][k][l][b][c] += dp[i][k][l][a][b];
              }
            }
          }
        }
      }
  }
  long long ans = 0;
  for (int a = 1; a < 5; ++a) {
    for (int b = 1; b < 5; ++b) {
      ans += dp[n][t][t - 1][a][b];
    }
  }
  cout << ans << "\n";
}
