#include <bits/stdc++.h>
using namespace std;
int const N=2002;
int tab[N][N],spi[N],spj[N];
 
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
    int n,m,zm;
    cin>>n>>m;
    for(int i=2;i<=n+1;i++) {
        cin>>tab[i][0];
        spi[i]=spi[i-1]+tab[i][0];
    }
    for(int i=1;i<=m;i++) {
        cin>>tab[0][i];
        spj[i]=spj[i-1]+tab[0][i];
    }
    for(int i=1;i<=n;i++){
        for(int j=1;j<=m;j++){
            tab[i][j]=max(spi[i]+spj[j-1]-tab[i][j-1]+tab[0][j],spi[i-1]+spj[j]-tab[i-1][j]+tab[i][0]);
        }
    }
    cout<<tab[n][m]<<' ';
}

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NiA2CjEgMTAgLTIgLTQgNiAtNQozIDQgLTEwIC0yIDAgMg==

6 6
1 10 -2 -4 6 -5
3 4 -10 -2 0 2