#include <iostream>
#include <vector>
#include <algorithm>
#include <atcoder/modint>

using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(n); i++)

using m32 = atcoder::modint998244353;

m32 dp[4001][4001];

int main(){
    int x,y; cin >> x >> y;
    if(4000 < x || 4000 < y) exit(0);
    dp[x][y] = 1;
    m32 ans = 0;
    for(int xx=x; xx>=0; xx--) for(int yy=y; yy>=0; yy--){
        m32 p = dp[xx][yy];
        if(xx == yy) ans += p;
        if(xx != 0) dp[xx-1][yy] += p;
        if(yy != 0) dp[xx][yy-1] += p;
        if(xx != 0 && yy != 0) dp[xx-1][yy-1] += p * 2;
    }
    cout << ans.val() << endl;
    return 0;
}




struct ios_do_not_sync {
    ios_do_not_sync() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} ios_do_not_sync_instance;