#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1e5 + 5;
const long long MOD = 998244353ll;
int N, M, K, Q, T;
int dp[1005][2005][4];
int main() {
  int i, j;
  scanf("%d%d", &N, &K);
  dp[1][1][0] = dp[1][1][3] = 1;
  dp[1][2][1] = dp[1][2][2] = 1;
  for (i = 2; i <= N; ++i) {
    for (int k = 0; k < 4; ++k) {
      for (j = 1; j <= K; ++j) {
        if (k == 0)
          dp[i][j][k] =
              ((long long)dp[i - 1][j][0] + (long long)dp[i - 1][j][1] +
               (long long)dp[i - 1][j][2] + (long long)dp[i - 1][j - 1][3]) %
              MOD;
        else if (k == 1)
          dp[i][j][k] =
              ((long long)dp[i - 1][j - 1][0] + (long long)dp[i - 1][j][1] +
               (long long)dp[i - 1][j - 2][2] +
               (long long)dp[i - 1][j - 1][3]) %
              MOD;
        else if (k == 2)
          dp[i][j][k] =
              ((long long)dp[i - 1][j - 1][0] + (long long)dp[i - 1][j - 2][1] +
               (long long)dp[i - 1][j][2] + (long long)dp[i - 1][j - 1][3]) %
              MOD;
        else if (k == 3)
          dp[i][j][k] =
              ((long long)dp[i - 1][j - 1][0] + (long long)dp[i - 1][j][1] +
               (long long)dp[i - 1][j][2] + (long long)dp[i - 1][j][3]) %
              MOD;
      }
    }
  }
  int res = 0;
  for (i = 0; i < 4; ++i) {
    res = ((long long)res + (long long)dp[N][K][i]) % MOD;
  }
  printf("%d", res);
  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;
const int MAXN = 1e5 + 5;
const long long MOD = 998244353ll;
int N, M, K, Q, T;
int dp[1005][2005][4];
int main() {
  int i, j;
  scanf("%d%d", &N, &K);
  dp[1][1][0] = dp[1][1][3] = 1;
  dp[1][2][1] = dp[1][2][2] = 1;
  for (i = 2; i <= N; ++i) {
    for (int k = 0; k < 4; ++k) {
      for (j = 1; j <= K; ++j) {
        if (k == 0)
          dp[i][j][k] =
              ((long long)dp[i - 1][j][0] + (long long)dp[i - 1][j][1] +
               (long long)dp[i - 1][j][2] + (long long)dp[i - 1][j - 1][3]) %
              MOD;
        else if (k == 1)
          dp[i][j][k] =
              ((long long)dp[i - 1][j - 1][0] + (long long)dp[i - 1][j][1] +
               (long long)dp[i - 1][j - 2][2] +
               (long long)dp[i - 1][j - 1][3]) %
              MOD;
        else if (k == 2)
          dp[i][j][k] =
              ((long long)dp[i - 1][j - 1][0] + (long long)dp[i - 1][j - 2][1] +
               (long long)dp[i - 1][j][2] + (long long)dp[i - 1][j - 1][3]) %
              MOD;
        else if (k == 3)
          dp[i][j][k] =
              ((long long)dp[i - 1][j - 1][0] + (long long)dp[i - 1][j][1] +
               (long long)dp[i - 1][j][2] + (long long)dp[i - 1][j][3]) %
              MOD;
      }
    }
  }
  int res = 0;
  for (i = 0; i < 4; ++i) {
    res = ((long long)res + (long long)dp[N][K][i]) % MOD;
  }
  printf("%d", res);
  return 0;
}

```