#include <fstream>
#include <algorithm>
using namespace std;
ifstream fin ("flip.in");
ofstream fout ("flip.out");
void  back(int k);
const int Dim = 17;
int A[Dim][Dim] , n, m , ma = -100000000 , s,Sl[Dim] , Sc[Dim];
bool UseL[Dim] = {0}, UseC[Dim] = {0};

int main() {
	fin >> n >> m;
	for(int i = 1; i <= n; i++)
		for(int j = 1; j <= m; j++)
			fin >> A[i][j] , s += A[i][j];
for(int i = 1; i <= n; i++)
	for(int j = 1; j <= m; j++) 
		Sl[i] += A[i][j];
for(int j = 1; j <= m; j++)
	for(int i = 1; i <= n; i++) 
		Sc[j] += A[i][j];	
back(0);
fout << ma;
 }
 
 int suma() {
 int S = 0;
 for(int i = 1; i <= n; i++)
	for(int j = 1; j <= m; j++)
		S += A[i][j];
return S;
 }
 
 void  back(int k ) {
	for(int i = k + 1; i <= n; i++) {
		for(int j = 1; j <= m; j++)
			A[i][j] *= -1;
		back(i+1);
		}
	for(int j = 1; j <= m; j++) {
		int ss = 0;
		for(int i = 1; i <= n ;i++)
			ss += A[i][j];
		if(ss < 0)
				for(int i = 1; i <= n ;i++)
						A[i][j] *= -1;
	
		}
	ma = max(ma,suma());	
}