#include <cstdio>
#include <vector>

using namespace std;

int n, m;
int mat[20][20];
vector<int> sol;
int maxSuma = 0;

void citire()
{
    scanf("%d %d", &n, &m);

    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < m; j++)
        {
            scanf("%d", &mat[i][j]);
            maxSuma += mat[i][j];
        }
    }
}

void calculareSuma()
{
    for(int i = 0; i < sol.size(); i++)
    {
        if(sol[i] < n)
        {
            for(int j = 0; j < m; j++)
            {
                mat[sol[i]][j] *= -1;
            }
        }
        else
        {
            for(int j = 0; j < n; j++)
            {
                mat[j][sol[i] - n] *= -1;
            }
        }
    }

    int suma = 0;

    for(int i = 0; i < n; i++)
    {
        for(int j = 0; j < m; j++)
        {
            suma += mat[i][j];
        }
    }

    if(suma > maxSuma)
    {
        maxSuma = suma;
    }

    for(int i = 0; i < sol.size(); i++)
    {
        if(sol[i] < n)
        {
            for(int j = 0; j < m; j++)
            {
                mat[sol[i]][j] *= -1;
            }
        }
        else
        {
            for(int j = 0; j < n; j++)
            {
                mat[j][sol[i] - n] *= -1;
            }
        }
    }
}

void backtracking()
{
    long long limita = (long long)1 << (n + m);

    for(long long k = 1; k < limita; k++)
    {
        sol.clear();

        for(int i = 0; i <= 32; i++)
        {
            if((k & (1 << i)) != 0)
            {
                sol.push_back(i);
            }
        }

        calculareSuma();
    }

    printf("%d", maxSuma);
}

int main()
{
    freopen("flip.in", "r", stdin);
    freopen("flip.out", "w", stdout);

    citire();
    backtracking();

    return 0;
}