#include <fstream>

using namespace std;

ifstream fin ("flip.in");
ofstream fout ("flip.out");

int main()
{
    int a[17][17], m, n;
    fin >> n >> m;

    for (int i = 1; i<=n; i++)
        for (int j = 1; j<=m; j++)
            fin >> a[i][j];

    int st =0;
    if (m >n)
    {
        int s;
        for (int i = 1; i<=n; i++)
        {
            s =0;
            for (int j = 1; j<=m; j++)s+=a[i][j];

            if (s < 0)
                for (int j = 1; j<=m; j++)a[i][j]*=-1;
        }
        for (int j = 1; j<=m; j++)
        {
            s =0;
            for (int i = 1; i<=n; i++)s+=a[i][j];

            if (s < 0)
            {
                for (int i = 1; i<=n; i++)a[i][j]*=-1;
                st+=s * -1;
            }
            else st+=s;
        }
    }
    else
    {
        int s;
        for (int j = 1; j<=m; j++)
        {
            s =0;
            for (int i = 1; i<=n; i++)s+=a[i][j];

            if (s < 0)for (int i = 1; i<=n; i++)a[i][j]*=-1;
        }

        for (int i = 1; i<=n; i++)
        {
            s =0;
            for (int j = 1; j<=m; j++)s+=a[i][j];

            if (s < 0)
            {
                for (int j = 1; j<=m; j++)a[i][j]*=-1;
                st+=s * -1;
            }
            else st+=s;
        }
    }
    fout  << st;
    return 0;
}