#include <fstream>
#include<iostream>

using namespace std;

int a[17][17], x[34], n, m, maxim, cmax, suma;

void flip() {
	int nr, i, j, b[17][17], s;
	
	cmax = suma;
	
	for ( i = 1; i <= n; i++ )
		for( j = 1; j <= m; j++ )
			b[i][j] = a[i][j];
		
	for ( i = 1; i <= n; i++ ) {
		if ( x[i] == 1 ) {
			for ( j = 1; j <= m; j++ ) {
				cmax = cmax - 2*b[i][j];
				b[i][j] = -b[i][j];
			}
		}			
	}
	
	for ( j = 1; j <= m; j++ ) {
		s = 0;
		for ( i = 1; i <= n; i++ )
			s = s + b[i][j];
		if ( s < 0 )
			for ( i = 1; i <= n; i++ ) {
				cmax = cmax - 2*b[i][j];
				b[i][j] = -b[i][j];
			}
	}
}

void back(int k) {
	for ( int i = 0; i <= 1; i++ )
		if ( k == n ) {
			x[k] = i;
			flip();
			if ( cmax > maxim )
				maxim = cmax;
		}
		else {
			x[k] = i;
			back(k+1);
		}
}

int main()
{
	
	ifstream f("flip.in");
	f >> n >> m;
	
	int i, j;
	for ( i = 1; i <= n; i++ )
		for( j = 1; j <= m; j++ )
			{
				f >> a[i][j];
			}
	for ( i = 1; i <= n; i++ )
		for( j = 1; j <= m; j++ )
			{
				maxim = maxim + a[i][j];
			}
	f.close();
	
	cmax = maxim;
	suma = cmax;
	
	back(1);
	
	ofstream g("flip.out");
	
	g<<maxim;
	
	g.close();
	
	return 0;
}