#include <bits/stdc++.h>

using namespace std;

int sum(int a[][100], int n, int m)
{
 	int s = 0;
 	for(int i = 0; i < n; i++)
 		for(int j = 0; j < m; j++)
 			s += a[i][j];
	return s;
}

void f(int a[][100], int n, int m, int col, int row)
{
	for(int i = 0; i < n; i++)
		a[i][col] *= -1;
	for(int j = 0; j < m; j++)
		a[row][j] *= -1;
}

int main() 
{
 	freopen("flip.in", "r", stdin);
 	freopen("flip.out", "w", stdout);	

 	int n, m, ans, mx;
 	cin >> n >> m;
 	int a[100][100];
 	for(int i = 0; i < n; i++)
 		for(int j = 0; j < m; j++)
 			cin >> a[i][j];
 	ans = mx = 0;
 	for(int i = 0; i < n; i++)
 		for(int j = 0; j < m; j++)
 		{
 			f(a, n, m, j, i);
 			ans = sum(a, n, m);
 			mx = max(mx, ans);
 			f(a, n, m, j, i);	 	
 		}
	cout << mx;
}