#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;
using mint=modint998244353;
mint dp[4040][4040];
int main()
{
    int x, y;cin>>x>>y;
  dp[0][0]=1;
  for(int i=0; i<=x; i++){
    for(int j=0; j<=y; j++){
      dp[i+1][j]+=dp[i][j];
      dp[i][j+1]+=dp[i][j];
      dp[i+1][j+1]+=2*dp[i][j];
    }
  }
  mint ans=0;
  for(int i=0; i<=min(x,y);i++){
    ans+=dp[x-i][y-i];
  }
  cout<<ans.val()<<endl;
    return 0;
}