#include <iostream>
#include <fstream>
using namespace std;
const
int main() {
int N, M;
int a[20][20], s, smax = 0;
ifstream f("flip.in");
ofstream g("flip.out");
f >> N>>M;
for(int i=0;i<N;i++)
for (int j = 0;j < M;j++)
{
f >> a[i][j];
}
for (int i = 0;i < N;i++)
{
s = 0;
for (int j = 0;j < M;j++)
{
s += a[i][j];
}
if (s < 0) {
for (int j = 0;j < M;j++)
{
a[i][j] = -a[i][j];
}
}
}
cout << endl;
for (int i = 0;i < M;i++)
{
s = 0;
for (int j = 0;j < N;j++)
{
s += a[j][i];
}
if (s < 0) {
for (int j = 0; j< N;j++)
{
a[j][i] = -a[j][i];
}
}
}
for (int i = 0;i < N;i++)
for (int j = 0;j < M;j++)
{
smax += a[i][j];
}
g << smax;
}