#include<stdio.h>

long a[20][20],i,j,n,m,max,p,sl,sc;
FILE *f,*g;
void verif()
{
int s;
s=0;
for (i=1;i<=n;i++)
 for (j=1;j<=m;j++) s=s+a[i][j];
  if (s>max) max=s ;

}

int main()
{   
	
f=fopen("flip.in","r+");
g=fopen("flip.out","w+");

fscanf(f,"%d %d",&n,&m);
max=0; 
for (i=1;i<=n;i++)
	for (j=1;j<=m;j++)
	{fscanf(f,"%d",&a[i][j]);max=max+a[i][j];};


for (p=1;p<=n*m;p++)
{	
for (i=1;i<=n;i++)
{
	sl=0;
	for (j=1;j<=m;j++) sl=sl+a[i][j];
if (sl<0) {for (j=1;j<=m;j++) a[i][j]=-a[i][j];
verif();
p=p-1; i=n+1;break;}

}

for (j=1;j<=m;j++)
{
	sc=0;
	for (i=1;i<=n;i++) sc=sc+a[i][j];
if (sc<0) {for (i=1;i<=n;i++) a[i][j]=-a[i][j];
verif();

 p=p-1;j=m+1;break;}

}

	
}
 fprintf(g,"%d",max);
 fclose(f);
 fclose(g);
 return 0;
}