#include <iostream>
#include <fstream>
using namespace std;

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

int a[17][17],i,j,k,n,m;

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

    int s=0,s1=0,s2=0,s3=0;
    for(i=1;i<=n;i++)
        {
            for(j=1;j<=m;j++)
                s1= a[i][j] + s1;
            if(s1<0)
                    for(j=1;j<=m;j++)
                            a[i][j] = a[i][j] * -1;
            s1=0;
        }


    s1=0;
    for(i=1;i<=m;i++)
    {
        for(j=1;j<=n;j++)
                s1 = s1+a[j][i];
        if(s1<0)
                for(j=1;j<=n;j++)
                        a[j][i] = a[j][i] * -1;
        s1=0;
    }

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

    g<<s;


    return 0;
}