#include <bits/stdc++.h>
using namespace std;
int n, m, a[20][20];

void Citire()
{ int i, j;
    ifstream fin("flip.in");
    fin >> n >>  m;

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

      fin.close();
}
void ComutareL(int i)
{ int j;
    for(j = 1; j <= m; j++)
        a[i][j] = a[i][j]*-1;
}
void ComutareC(int j)
{ int i;
    for(i = 1; i <= n; i++)
        a[i][j] = a[i][j]*-1;
}
void Flip()
{
    int i,j, sl, sc;
    for(i = 1; i <= n; i++)
    {
        sl = 0;

        for(j = 1; j <= m; j++)
            sl += a[i][j];

        if(sl < 0) ComutareL(i);

    }
     for(j = 1; j <= m; j++)
    {
        sc = 0;

        for(i = 1; i <= n; i++)
            sc += a[i][j];

        if(sc < 0) ComutareC(j);

    }

}

int main()
{
    Citire();
    Flip();\
    int s = 0;
    for(int i = 1; i <= n; i++)
        for(int j = 1; j <= m; j++)
          s+= a[i][j];
    ofstream fout("flip.out");
    fout << s << "\n";
    return 0;
}