C++ :

/*
	author :hzoi_ztx
	title  :mine 
	ALG    :dp 
	comment:

	[2014 10 20]
*/

#include <cstdio>

#define  maxn  1005

int n , m , ans ;
int sa[maxn][maxn] = {0} ;
int sb[maxn][maxn] = {0} ;
int f[maxn][maxn][2] = {0} ;

int main() {
	//#define  READ
	#ifdef   READ
		freopen("mine.in" ,"r",stdin ) ;
		freopen("mine.out","w",stdout) ;
	#endif
	int i , j ;
	scanf("%d%d", &n , &m ) ;
	for (i = 1 ; i <= n ; i ++ )
		for (j = 1 ; j <= m ; j ++ ) {
			scanf("%d", &sa[i][j] ) ;
			sa[i][j] += sa[i][j-1] ;
		}
	for (i = 1 ; i <= n ; i ++ )
		for (j = 1 ; j <= m ; j ++ ) {
			scanf("%d", &sb[i][j] ) ;
			sb[i][j] += sb[i-1][j] ;
		}
	for (i = 1 ; i <= n ; i ++ ) {
		for (j = 1 ; j <= m ; j ++ ) {
			//东西 0
			if (f[i-1][j][1] > f[i-1][j][0]) f[i][j][0] = f[i-1][j][1]+sa[i][j] ;
			else f[i][j][0] = f[i-1][j][0]+sa[i][j] ;
			//南北 1
			if (f[i][j-1][1] > f[i][j-1][0]) f[i][j][1] = f[i][j-1][1]+sb[i][j] ;
			else f[i][j][1] = f[i][j-1][0]+sb[i][j] ;
		}
	}
/*	printf("nanbei ：\n") ;
	for (i = 1 ; i <= n ; i ++ ) {
		printf("\n") ;
		for (j = 1 ; j <= m ; j ++ ) printf("%d ",f[i][j][1]) ;
	}
	printf("\ndongxi : \n") ;
	for (i = 1 ; i <= n ; i ++ ) {
		printf("\n") ;
		for (j = 1 ; j <= m ; j ++ ) printf("%d ",f[i][j][0]) ;
	}
*/
	if (f[n][m][1]>f[n][m][0]) f[n][m][0] = f[n][m][1] ;
	printf("%d\n", f[n][m][0]);
	#ifdef   READ
		fclose(stdin ) ;
		fclose(stdout) ;
	#endif
	return 0 ;
}