#include <bits/stdc++.h>
using namespace std;
static int dp[1000][2000][4];
int main() {
  int n, ak;
  cin >> n >> ak;
  dp[0][0][0] = 0;
  dp[0][0][1] = 0;
  dp[0][0][2] = 0;
  dp[0][0][3] = 0;
  dp[0][1][0] = 1;
  dp[0][1][1] = 0;
  dp[0][1][2] = 0;
  dp[0][1][3] = 1;
  dp[0][2][0] = 0;
  dp[0][2][1] = 1;
  dp[0][2][2] = 1;
  dp[0][2][3] = 0;
  for (int i = 0; i < n - 1; ++i) {
    for (int k = 1; k <= ak; ++k) {
      dp[i + 1][k][0] = ((long long)dp[i][k][0] + dp[i][k][1] + dp[i][k][2] +
                         dp[i][k - 1][3]) %
                        998244353;
      dp[i + 1][k][1] = ((long long)dp[i][k - 1][0] + dp[i][k][1] +
                         dp[i][k - 2][2] + dp[i][k - 1][3]) %
                        998244353;
      dp[i + 1][k][2] = ((long long)dp[i][k - 1][0] + dp[i][k][1] +
                         dp[i][k - 2][2] + dp[i][k - 1][3]) %
                        998244353;
      dp[i + 1][k][3] = ((long long)dp[i][k - 1][0] + dp[i][k][1] +
                         dp[i][k][2] + dp[i][k][3]) %
                        998244353;
    }
  }
  long long ans = (long long)dp[n - 1][ak][0] + dp[n - 1][ak][1] +
                  dp[n - 1][ak][2] + dp[n - 1][ak][3];
  cout << ans % 998244353;
  return 0;
}

### Prompt

Generate a Cpp solution to the following problem:

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;
static int dp[1000][2000][4];
int main() {
  int n, ak;
  cin >> n >> ak;
  dp[0][0][0] = 0;
  dp[0][0][1] = 0;
  dp[0][0][2] = 0;
  dp[0][0][3] = 0;
  dp[0][1][0] = 1;
  dp[0][1][1] = 0;
  dp[0][1][2] = 0;
  dp[0][1][3] = 1;
  dp[0][2][0] = 0;
  dp[0][2][1] = 1;
  dp[0][2][2] = 1;
  dp[0][2][3] = 0;
  for (int i = 0; i < n - 1; ++i) {
    for (int k = 1; k <= ak; ++k) {
      dp[i + 1][k][0] = ((long long)dp[i][k][0] + dp[i][k][1] + dp[i][k][2] +
                         dp[i][k - 1][3]) %
                        998244353;
      dp[i + 1][k][1] = ((long long)dp[i][k - 1][0] + dp[i][k][1] +
                         dp[i][k - 2][2] + dp[i][k - 1][3]) %
                        998244353;
      dp[i + 1][k][2] = ((long long)dp[i][k - 1][0] + dp[i][k][1] +
                         dp[i][k - 2][2] + dp[i][k - 1][3]) %
                        998244353;
      dp[i + 1][k][3] = ((long long)dp[i][k - 1][0] + dp[i][k][1] +
                         dp[i][k][2] + dp[i][k][3]) %
                        998244353;
    }
  }
  long long ans = (long long)dp[n - 1][ak][0] + dp[n - 1][ak][1] +
                  dp[n - 1][ak][2] + dp[n - 1][ak][3];
  cout << ans % 998244353;
  return 0;
}

```