#include<iostream>
#include<fstream>
using namespace std;

ifstream in ("flip.in");
ofstream out("flip.out");
const int N = 16;
int mat[N][N];
int n, m;

inline int max(int x, int y)
{
    return (x > y) ? x : y;
}
int sum(int cn, int cm)
{
    int rez = 0;
    for(int i = 0; i < n; i++)
        for(int j = 0; j < m; j++)
        {
            bool negative_row = cn & (1 << i);
            bool negative_col = cm & (1 << j);
            bool negative = negative_row ^ negative_col;
            rez += negative ? -mat[i][j] : mat[i][j];
        }
    return rez;
}
int main()
{
    in >> n >> m;
    for(int i = 0; i < n; i++)
        for(int j = 0; j < m; j++)
            in >> mat[i][j];

    int max_sum = sum(0, 0);
    for(int cn = 1 << n - 1; cn >= 0; cn--)
        for(int cm = 1 << m - 1; cm >= 0; cm--)
            max_sum = max(max_sum, sum(cn, cm));
    out << max_sum << '\n';
    return 0;
}