#include <stdio.h>

const int Mod = 998244353;
long long memo[501][501];

long long recursion(int N, int M)
{
	if (memo[N][M] >= 0) return memo[N][M];
	else memo[N][M] = 0;
	
	int i;
	memo[N][M] += recursion(N - 1, 0) * (recursion(N - 1, M) + recursion(N - 1, M - 1)) % Mod;
	for (i = 1; i < M; i++) memo[N][M] += recursion(N - 1, i) * recursion(N - 1, M - i - 1) % Mod;
	memo[N][M] %= Mod;
	return memo[N][M];
}

int main()
{
	int N, M;
	scanf("%d %d", &N, &M);
	
	int i, j;
	for (i = 0; i <= N; i++) for (j = 1, memo[i][0] = 1; j <= M; j++) memo[i][j] = -1;
	for (j = 2, memo[1][0] = 1, memo[1][1] = 1; j <= M; j++) memo[1][j] = 0;
	printf("%lld\n", recursion(N, M));
	fflush(stdout);
	return 0;
}