#include <bits/stdc++.h>
using namespace std;
int n, m;
int dp[25][15][15][5][5];
int main() {
  cin >> n >> m;
  memset(dp, 0, sizeof(dp));
  for (int i = 1; i <= 4; i++)
    for (int j = i + 1; j <= 4; j++) dp[2][0][0][i][j] = 1;
  for (int i = 2; i <= n; i++)
    for (int x = 0; x <= m; x++)
      for (int y = 0; y <= m; y++)
        for (int prev = 1; prev <= 4; prev++)
          for (int now = 1; now <= 4; now++)
            if (dp[i][x][y][prev][now])
              for (int next = 1; next <= 4; next++) {
                if (now > prev && now > next)
                  dp[i + 1][x + 1][y][now][next] += dp[i][x][y][prev][now];
                if (now < prev && now < next)
                  dp[i + 1][x][y + 1][now][next] += dp[i][x][y][prev][now];
                if (now > prev && now < next)
                  dp[i + 1][x][y][now][next] += dp[i][x][y][prev][now];
                if (now < prev && now > next)
                  dp[i + 1][x][y][now][next] += dp[i][x][y][prev][now];
              }
  int ans = 0;
  for (int now = 1; now <= 4; now++)
    for (int prev = 1; prev <= 4; prev++) ans += dp[n][m][m - 1][prev][now];
  cout << ans << endl;
  return 0;
}
