import std.conv, std.functional, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.complex, std.container, std.math, std.numeric, std.range, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


enum long MO = 998244353;
enum LIM = 10^^5;

long[] inv, fac, invFac;
void prepare() {
  inv = new long[LIM];
  fac = new long[LIM];
  invFac = new long[LIM];
  inv[1] = 1;
  foreach (i; 2 .. LIM) {
    inv[i] = MO - ((MO / i) * inv[cast(size_t)(MO % i)]) % MO;
  }
  fac[0] = invFac[0] = 1;
  foreach (i; 1 .. LIM) {
    fac[i] = (fac[i - 1] * i) % MO;
    invFac[i] = (invFac[i - 1] * inv[i]) % MO;
  }
}
long binom(long n, long k) {
  if (0 <= k && k <= n) {
    assert(n < LIM);
    return fac[cast(size_t)(n)] * invFac[cast(size_t)(k)] % MO * invFac[cast(size_t)(n - k)] % MO;
  } else {
    return 0;
  }
}


int N, X;

void main() {
  prepare();
  
  try {
    for (; ; ) {
      N = readInt();
      X = readInt();
      
      long ans;
      
      if (X == 1) {
        // 0, 2
        ans = 1;
        foreach (i; 0 .. N) {
          ans *= 2;
          ans %= MO;
        }
      } else {
        auto dp = new long[][](X + 1, X + 1);
        dp[0][1] = 1;
        foreach (i; 0 .. X) {
          foreach (a; 0 .. X + 1) {
            foreach (j; [i + 1, i + 2]) {
              if (j <= X && a + 1 <= X) {
                dp[j][a + 1] += dp[i][a];
                dp[j][a + 1] %= MO;
              }
            }
          }
        }
        debug {
          if (X <= 10) {
            writeln("dp = ", dp);
          }
        }
        foreach (s; 0 .. X) {
          /*
            o ... o
          */
          long tmp;
          foreach (a; 1 .. X + 1) {
            if (a <= N + 1) {
              // a multi-choose (N + 1) - a
              tmp += (dp[s][a] * binom(a + ((N + 1) - a) - 1, (N + 1) - a)) % MO;
              tmp %= MO;
            }
          }
          debug {
            if (X <= 13) {
              writefln("s = %s: %s", s, tmp);
            }
          }
          ans += tmp;
          ans %= MO;
        }
        foreach (s; X .. 2 * X - 1) {
          if ((s - X) % 2 != 0) {
            long tmp;
            foreach (a; 1 .. X + 1) {
              const b = (s - X + 1) + a;
              if (b <= N + 1) {
                tmp += (dp[X - 1 - (s - X + 1)][a] * binom(b + ((N + 1) - b) - 1, (N + 1) - b)) % MO;
                tmp %= MO;
              }
            }
            debug {
              if (X <= 13) {
                writefln("s = %s: %s", s, tmp);
              }
            }
            ans += tmp;
            ans %= MO;
          }
        }
        if (X % 2 != 0) {
          int cnt = X;
          foreach (s; 2 * X .. 2 * N + 1) {
            const q = s / X, r = s % X;
            if ((q + r) % 2 == 0) {
              ++cnt;
              if (cnt <= N + 1) {
                const tmp = binom(cnt + ((N + 1) - cnt) - 1, (N + 1) - cnt);
                debug {
                  if (X <= 13) {
                    writefln("s = %s: %s", s, tmp);
                    writefln("  cnt = %s", cnt);
                  }
                }
                ans += tmp;
                ans %= MO;
              }
            }
          }
        }
      }
      ans = (ans % MO + MO) % MO;
      writeln(ans);
    }
  } catch (EOFException e) {
  }
}


Measured memory_bytes: 292988