#include <iostream>
#include <fstream>

using namespace std;

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

int main()
{ 
	int a[17][17],n,m,i,j,s;
	//citire matrice
	fin>>n>>m;
	for (i=1;i<=n;i++)
	{
	for (j=1;j<=m;j++)
		fin>>a[i][j];}
	//verificare linie
	for (i=1;i<=n;i++)
	{	s=0;
		for (j=1;j<=m;j++)
	{
	s=s+a[i][j];}
		if (s<0)
		{	a[i][j]=a[i][j]*(-1);}
	}
	//verificare linie
	for (j=1;j<=m;j++)
	{	s=0;
		for (i=1;i<=n;i++)
		{s=s+a[i][j];}
		if (s<0)
		{a[i][j]=a[i][j]*(-1);}
	}
	//suma maxima
	s=0;
	for (i=1;i<=n;i++)
	{for (j=1;j<=m;j++)
	s=s+a[i][j];}
	fout<<s;
	return 0;
}