#include <iostream>

using namespace std;
#define DIM_MAX 200
#define MAX(x,y) (x)>(y)?(x):(y)
ifstream fin("flip.in");
ofstream fout("flip.out");

int n,m,matrice[DIM_MAX][DIM_MAX];
void citire(long sum)
{
    fin>>n>>m;
    for(i=0;i<n;++i)
        for(j=0;j<m;++j)
        {
           fin>>matrice[i][j];
           sum+=matrice[i][j];
        }
}
long suma(int matrix[DIM_MAX][DIM_MAX] ,int lin, int col)
{
    if(lin==n && col==m)
        return matrix[lin][col];
    if(col==n)
        return matrix[lin][col]+suma(lin+1,1);
    return matrix[lin][col]+suma(lin,col+1)
}
int **comutator(int vector[DIM_MAX][DIM_MAX],int lin, int col)
{
    int **place_holder = vector ;
    if(col==0)
    for(int i=0;i<n;i++)
        place_holder[lin][i] *= -1;
    else
    for(int i=0;i<n;i++)
        place_holder[i][col] *= -1;
    return place_holder;
}
int suma_max()
{
    return MAX(suma(comutator(matrice,1,0),1,1),suma(comutator(matrice,0,1),1,1))
}
int main()
{
    int lin, col;
    long sum;
    citire(sum);
    fout<<suma_max();
    return 0;
}