#include <iostream>
#include <fstream>
#include <math.h>

using namespace std;
int n, m, **matrix;
unsigned short nplace = 0, mplace = 0, aux;
short retv(unsigned short a, int b)
{
    aux = a>>b;
    if(aux %2 == 0) return 1;
    else return -1;
}
int sum()
{
    int j, s=0;
    for(int i = 0; i<n; i ++)
        for(j = 0; j< m; j++)
            s += matrix[i][j]*retv(nplace, i)* retv(mplace, j);
    return s;
}
int main()
{
    int i, j;
    ifstream* mystream;
    mystream = new ifstream("flip.in");
    *mystream>>n;
    *mystream >> m;
    //create matrix
    matrix = new int*[n];
    for(i = 0; i<n; i++)
        matrix[i] = new int[m];
    //read matrix v. daca nu incurci lin cu col
    for(i = 0; i<n; i++)
        for(j = 0; j<m; j++)
            *mystream>> matrix[i][j];
    mystream->close();
    int mysum, csum = 0;
    int maxn = pow(2, n), maxm = pow(2, m);
    for(nplace = 0; nplace< maxn; nplace ++)
        for(mplace = 0; mplace< maxm-1; mplace ++)
        {
            mysum = sum();
            if (csum<mysum) csum = mysum;
        }
        ofstream stream("flip.out");
        stream<<csum;stream.close();
        return 0;
    }