#include<bits/stdc++.h>
#define int long long
#define p 998244353 
using namespace std;

int n,m,f[501][501],ans;
int pw[250001];

signed main(){
    ios::sync_with_stdio(false); 
    freopen("theory.in","r",stdin);
    freopen("theory.out","w",stdout);
    cin>>n>>m;
    pw[0]=1;
    for(int i=1;i<=n*n;i++)pw[i]=pw[i-1]*2%p;
    f[0][0]=1;
    if(m==0){
        cout<<1;return 0;
    }
    for(int i=0;i<=n;i++){
        for(int k=i+1;k<=n;k++){
            for(int j=0;j<=n;j++){
                f[k][j+1]+=f[i][j]*(pw[k-i]-1)%p*pw[(n-k)*(k-i)]%p;
                f[k][j+1]%=p;
            }
        }
    }
    for(int i=1;i<=n;i++){
        ans+=f[i][m];ans%=p;
    } 
    cout<<ans;
}