#include <bits/stdc++.h>
#define forn(i,s,t) for(int i = (s); i <= (t); ++i)
using namespace std;
const int N = 4004, Mod = 998244353;
int f[N][N], n, m;
int main() {
	scanf("%d%d", &n, &m);
	f[0][0] = 1;
	forn (i, 0, n) forn (j, 0, m) if (i != 0 || j != 0) {
		if (i) f[i][j] += f[i - 1][j];
		if (j) f[i][j] += f[i][j - 1];
		f[i][j] %= Mod;
		if (i && j) f[i][j] += 2ll * f[i - 1][j - 1] % Mod;
		f[i][j] %= Mod;
	}
	int res = 0;
	forn (i, 0, min(n, m)) res = (res + f[n - i][m - i]) % Mod;
	printf("%d\n", res);
	return 0;
}