#include <stdio.h>

int m,n, a[16][16];
int x,y, max;
//--------------------------------
void read()
{
	int i,j;
	FILE *f = fopen("flip.in","rt");
	fscanf(f,"%d %d", &n,&m);
	for(i=0; i<n; i++)
		for(j=0; j<m; j++)
			fscanf(f,"%d", &a[i][j]);
	fclose(f);
}
//--------------------------------
void sum()
{
	int i,j, s = 0;
	for(i=0; i<n; i++)
		for(j=0; j<m; j++)
			s += a[i][j]*((x>>i) & 1? -1: 1)*((y>>j) & 1? -1: 1);
	if(max < s)
		max = s;
}
//--------------------------------
void solve()
{
	max = -1000;
	for(x=0; x < (1<<n); x++)
		for(y=0; y < (1<<m); y++)
			sum();
}
//--------------------------------
void print()
{
	FILE *f = fopen("flip.out","wt");
	fprintf(f,"%d", max);
	fclose(f);
}
//--------------------------------
int main(void)
{
	read();
	solve();
	print();
	return 0;
}