#include <bits/stdc++.h>
long long f[22][22][22][6][6];
int n, q;
void init(void) {
  scanf("%d", &n);
  scanf("%d", &q);
}
void optimize(void) {
  int i, j, k, l, m, t;
  for (i = 1; i <= 4; i = i + 1)
    for (j = 1; j <= 4; j = j + 1)
      if (i != j) f[2][0][0][i][j]++;
  for (i = 1; i < n; i = i + 1)
    for (j = 0; j <= n; j = j + 1)
      for (k = 0; k <= n; k = k + 1)
        for (l = 1; l <= 4; l = l + 1)
          for (m = 1; m <= 4; m = m + 1)
            if (f[i][j][k][l][m] > 0LL)
              for (t = 1; t <= 4; t = t + 1)
                if (t != m)
                  f[i + 1][j + (l < m && m > t)][k + (l > m && m < t)][m][t] +=
                      f[i][j][k][l][m];
  long long res = 0LL;
  for (i = 1; i <= 4; i = i + 1)
    for (j = 1; j <= 4; j = j + 1)
      if (i != j) res += f[n][q][q - 1][i][j];
  printf("%I64d", res);
}
int main(void) {
  init();
  optimize();
  return 0;
}
