#include <fstream>

#define DEBUG 1

#ifdef DEBUG
	#include <iostream>
#endif

int mM[16], nM[16];

int main()
{
	std::ifstream in("flip.in");
	std::ofstream out("flip.out");

	int m, n, v[n], S = 0;
	in >> m >> n;

	for (short i=0; i<m; ++i)
	{
		for (short j=0; j<n; ++j)
		{
			in >> v[j];
			mM[i] += v[j];
			nM[j] += v[j];
			S += v[j];
		}
		if (mM[i]<0)
		{
			S -= mM[i];
			S += (-1) * mM[i];
			for (short j=0; j<n; ++j)
			{
				nM[j] -= v[j];
				nM[j] += v[j] * (-1); 
			}
		}
	}

	for (short i=0; i<n; ++i)
	{
		if (nM[i]<0)
		{
			S -= nM[i];
			S += (-1) * nM[i];
		}
	}

	out << S;
	return 0;
}