#include <bits/stdc++.h>
using namespace std;
int N, T;
int best[5][5][22][12][12];
int go(int y1, int y2, int n, int humps, int unhumps) {
  int& res = best[y1][y2][n][humps][unhumps];
  if (res != -1) return res;
  if (n > N) {
    if (humps == 0 && unhumps == 0)
      return res = 1;
    else
      return res = 0;
  }
  res = 0;
  for (int y3 = 1; y3 < 5; ++y3) {
    if (y3 == y2) continue;
    if (y3 > y2) {
      if (y2 > y1)
        res += go(y2, y3, n + 1, humps, unhumps);
      else if (y1 > y2 && unhumps > 0)
        res += go(y2, y3, n + 1, humps, unhumps - 1);
    } else {
      if (y2 > y1 && humps > 0)
        res += go(y2, y3, n + 1, humps - 1, unhumps);
      else if (y1 > y2)
        res += go(y2, y3, n + 1, humps, unhumps);
    }
  }
  return res;
}
int main(int argc, char* argv[]) {
  memset(best, -1, sizeof(best));
  N, T;
  cin >> N >> T;
  int res = 0;
  for (int y1 = 1; y1 < 5; ++y1) {
    for (int y2 = 1; y2 < 5; ++y2) {
      if (y1 == y2) continue;
      res += go(y1, y2, 3, T, T - 1);
    }
  }
  cout << res << "\n";
}
