#include <iostream>

 #include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<stdlib.h>

 using namespace std;

 int dp[][];

 int n,m;

 int a[][];

 int b[][];

 int dfs(int i,int j)

 {

     if(i<||j<)

     return ;

     if(dp[i][j]!=-)

     return dp[i][j];

     int g,s1=,s2=;

     for(g =  ; g <= i ; g++)

     s1+=b[g][j];

     for(g = ; g <= j ; g++)

     s2+=a[i][g];

     dp[i][j] = max(dfs(i-,j)+s2,dfs(i,j-)+s1);

     return dp[i][j];

 }

 int main()

 {

     int i,j;

     while(scanf("%d%d",&n,&m)!=EOF)

     {

         if(n==&&m==)

         break;

         memset(dp,-,sizeof(dp));

         for(i = ; i <= n ; i++)

             for(j =  ; j <= m ; j++)

             scanf("%d",&a[i][j]);

         for(i = ; i <= n ; i++)

             for(j =  ; j <= m ; j++)

             scanf("%d",&b[i][j]);

         int ans  = dfs(n,m);

         printf("%d\n",ans);

     }

     return ;

 }