#include <bits/stdc++.h>
using namespace std;
int n, m, f[25][5][5][25][25];
inline int read() {
  int ret = 0, ff = 1;
  char ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') ff = -1;
    ch = getchar();
  }
  while (isdigit(ch)) {
    ret = ret * 10 + (ch ^ 48);
    ch = getchar();
  }
  return ret * ff;
}
void write(int x) {
  if (x < 0) {
    x = -x, putchar('-');
  }
  if (x > 9) write(x / 10);
  putchar(x % 10 + 48);
}
void writeln(int x) { write(x), puts(""); }
void writesp(int x) { write(x), putchar(' '); }
signed main() {
  n = read(), m = read();
  if (n < m * 2 + 1) {
    write(0);
    return 0;
  }
  for (int i = 1; i <= 4; i++)
    for (int j = 1; j <= 4; j++)
      if (i != j) f[2][i][j][0][0] = 1;
  for (int now = 2; now <= n; now++)
    for (int s1 = 0; s1 <= m; s1++)
      for (int s2 = 0; s2 <= m - 1; s2++)
        for (int i = 1; i <= 4; i++)
          for (int j = 1; j <= 4; j++)
            for (int k = 1; k <= 4; k++) {
              if (j > i && i < k)
                f[now + 1][k][i][s1][s2 + 1] += f[now][i][j][s1][s2];
              else if (j < i && i > k)
                f[now + 1][k][i][s1 + 1][s2] += f[now][i][j][s1][s2];
              else if (j != i && i != k)
                f[now + 1][k][i][s1][s2] += f[now][i][j][s1][s2];
            }
  int ans = 0;
  for (int i = 1; i <= 4; i++)
    for (int j = 1; j <= 4; j++)
      if (i != j) ans += f[n][i][j][m][m - 1];
  write(ans);
  return 0;
}
