#include <iostream>
#include <fstream>

using namespace std;

ifstream fi("flip.in");
ofstream fo("flip.out");

int main()
{
    int n, m, s = 0, a[1000][1000];
    
    fi>>n>>m;
    
    for(int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            fi>>a[i][j];
    
    
    for(int i = 0; i < n; i++)
    {
        int s_local_1 = 0, s_local_2 = 0;
        
        for (int j = 0; j < m; j++)
        {
            s_local_1 += a[i][j];
        }
        
        for (int j = 0; j < m; j++)
        {
            s_local_2 = s_local_2 + (a[i][j]*(-1));
        }
        
        if (s_local_1 < s_local_2)
        {
            for (int j = 0; j < m; j++)
                a[i][j] *= -1;
        }
    }
    
    for(int i = 0; i < m; i++)
    {
        int s_local_1 = 0, s_local_2 = 0;
        
        for (int j = 0; j < n; j++)
        {
            for (int j = 0; j < n; j++)
            {
                s_local_1 += a[j][i];
            }
            
            for (int j = 0; j < n; j++)
            {
                s_local_2 = s_local_2 + (a[j][i]*(-1));
            }
            
            if (s_local_1 < s_local_2)
            {
                for (int j = 0; j < n; j++)
                    a[j][i] *= -1;
            }

            
        }
    }
    
    for(int i = 0; i < n; i++)
        for (int j = 0; j < m; j++)
            s += a[i][j];
    
    
    fo<<s;
    
    fo.close();
    return 0;
}