#include <fstream>

using namespace std;

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

int main()
{
    int n;
    int m;
    int A[16][16];
    fin >> n >> m;
    for (int i = 0; i<n; ++i)
        for (int j = 0; j<m; ++j)
            fin >> A[i][j];

    int sum_plus, sum_min;

    for (int i = 0; i<n; ++i)
    {
        sum_plus = 0; sum_min = 0;
        for (int j = 0; j<m; ++j)
        {
            sum_plus+=A[i][j];
            sum_min+=-1*A[i][j];
        }

        if (sum_min  > sum_plus)
            for (int k = 0; k<m; ++k)
                A[i][k]  = A[i][k] *(-1);

    }

    for (int i = 0; i<m; ++i)
    {
        sum_plus = 0; sum_min = 0;
        for (int j = 0; j<n; ++j)
        {
            sum_plus+=A[j][i];
            sum_min+=-1*A[j][i];
        }

        if (sum_min  > sum_plus)
            for (int k = 0; k<n; ++k)
                A[k][i]  = A[k][i] *(-1);

    }

    int sum  =  0;
    for (int i = 0; i<n; ++i)
        for (int j = 0; j<m; ++j)
            sum+=A[i][j];

    fout <<  sum;

    return 0;

}