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

const int M = 16;
const int N = 16;
int v[M][N];
int nr1, nr2, Smax, Smin, m, n;


int main(void)
{
	ifstream fin("flip.in", ios::in);
	ofstream fout("flip.out", ios::out);
	fin >> nr1;
	fin >> nr2;
	//initializare matrice
	for (int i = 0; i < nr1; i++)
	{
		for (int j = 0; j < nr2; j++)
		{
			fin >> m;
			v[i][j] = m;
			Smax += v[i][j];
			//fout << v[i][j]<<" "; //asta trebuie scoasa
			v[i][j] = -m;
			Smin += v[i][j];
			if (Smin>Smax)
			{
				n = Smin;
				Smin = Smax;
				Smax = n;
			}
		}
		//fout << endl;
	}

	fout << Smax << endl;;
	//fout << Smin;


}