#include <bits/stdc++.h>
using namespace std;
long long dp[1001][2001][4];
int main() {
  int n, k;
  cin >> n >> k;
  dp[0][1][0] = dp[0][1][3] = 1;
  dp[0][2][1] = dp[0][2][2] = 1;
  for (int x = 1; x < n; x++) {
    for (int y = 1; y <= 2000; y++) {
      dp[x][y][0] = (dp[x - 1][y][0] + dp[x - 1][y][1] + dp[x - 1][y][2] +
                     dp[x - 1][y - 1][3]) %
                    998244353;
      dp[x][y][1] = (dp[x - 1][y - 1][0] + dp[x - 1][y][1] +
                     (y == 1 ? 0 : dp[x - 1][y - 2][2]) + dp[x - 1][y - 1][3]) %
                    998244353;
      dp[x][y][2] = (dp[x - 1][y - 1][0] + (y == 1 ? 0 : dp[x - 1][y - 2][1]) +
                     dp[x - 1][y][2] + dp[x - 1][y - 1][3]) %
                    998244353;
      dp[x][y][3] = (dp[x - 1][y - 1][0] + dp[x - 1][y][1] + dp[x - 1][y][2] +
                     dp[x - 1][y][3]) %
                    998244353;
    }
  }
  long long ans =
      (dp[n - 1][k][0] + dp[n - 1][k][1] + dp[n - 1][k][2] + dp[n - 1][k][3]) %
      998244353;
  cout << ans << endl;
  return 0;
}

### Prompt

Develop a solution in CPP to the problem described below:

You are given a grid, consisting of 2 rows and n columns. Each cell of this grid should be colored either black or white.

Two cells are considered neighbours if they have a common border and share the same color. Two cells A and B belong to the same component if they are neighbours, or if there is a neighbour of A that belongs to the same component with B.

Let's call some bicoloring beautiful if it has exactly k components.

Count the number of beautiful bicolorings. The number can be big enough, so print the answer modulo 998244353.

Input

The only line contains two integers n and k (1 ≤ n ≤ 1000, 1 ≤ k ≤ 2n) — the number of columns in a grid and the number of components required.

Output

Print a single integer — the number of beautiful bicolorings modulo 998244353.

Examples

Input

3 4


Output

12


Input

4 1


Output

2


Input

1 2


Output

2

Note

One of possible bicolorings in sample 1:

<image>

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
long long dp[1001][2001][4];
int main() {
  int n, k;
  cin >> n >> k;
  dp[0][1][0] = dp[0][1][3] = 1;
  dp[0][2][1] = dp[0][2][2] = 1;
  for (int x = 1; x < n; x++) {
    for (int y = 1; y <= 2000; y++) {
      dp[x][y][0] = (dp[x - 1][y][0] + dp[x - 1][y][1] + dp[x - 1][y][2] +
                     dp[x - 1][y - 1][3]) %
                    998244353;
      dp[x][y][1] = (dp[x - 1][y - 1][0] + dp[x - 1][y][1] +
                     (y == 1 ? 0 : dp[x - 1][y - 2][2]) + dp[x - 1][y - 1][3]) %
                    998244353;
      dp[x][y][2] = (dp[x - 1][y - 1][0] + (y == 1 ? 0 : dp[x - 1][y - 2][1]) +
                     dp[x - 1][y][2] + dp[x - 1][y - 1][3]) %
                    998244353;
      dp[x][y][3] = (dp[x - 1][y - 1][0] + dp[x - 1][y][1] + dp[x - 1][y][2] +
                     dp[x - 1][y][3]) %
                    998244353;
    }
  }
  long long ans =
      (dp[n - 1][k][0] + dp[n - 1][k][1] + dp[n - 1][k][2] + dp[n - 1][k][3]) %
      998244353;
  cout << ans << endl;
  return 0;
}

```