#include <fstream>
using namespace std;

ifstream cin("flip.in");
ofstream cout("flip.out");

void back(int m, int n);
int sum(int m, int n);
void comutare(int i, int j, int m, int n);

int A[16][16], B[16][16];

int main()
{
    int m, n, s = 0, tmp;
    cin>>m>>n;
    for (int i = 0; i < m; i++)
    {
        for (int j = 0; j < n; j++)
        {
            cin>>A[i][j];
            B[i][j] = A[i][j];
        }
    }
    for (int i = 0; i < m; i++)
    {
        for (int j = 0; j < n; j++)
        {
            comutare(i, j, m, n);
            tmp = sum(m,n);
            if (tmp > s)
                s = tmp;
            back(m, n);
        }   
    }
    cout<<s;
    cin.close();
    cout.close();
    return 0;
}

void back(int m, int n)
{
    for(int i = 0; i < m; i++)
    {
        for (int j = 0; j < n; j++)
            A[i][j] = B[i][j];
    }
}
int sum(int m, int n)
{
    int s = 0;
    for(int i = 0; i < m; i++)
    {
        for (int j = 0; j < n; j++)
            s += A[i][j];
    }
    return s;
}
void comutare(int i, int j, int m, int n)
{
    for (int k = 0; k < m; k++)
    {
        A[k][i] = -A[k][i];
    }
    for (int k = 0; k < n; k++)
    {
        A[j][k] = -A[j][k];
    }
}