#include <iostream>
#include <fstream>

std::ifstream f("flip.in");
std::ofstream g("flip.out");

int main()
{
        int n, m;
        int a[20][20];

        f >> n >> m;

        for (int i = 0; i < n; i++)
                for (int j = 0; j < m; j++)
                        f >> a[i][j];

        int normalSum, flippedSum;
        for (int i = 0; i < n; i++)
        {
                normalSum = 0;
                flippedSum = 0;

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

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

        for (int i = 0; i < m; i++)
        {
             normalSum = 0;
                flippedSum = 0;

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

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

        }

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

        g << totalSum;

        return 0;
}