#include <iostream.h>
#include <stdio.h>


int n,m;
long int max;
long int a[17][17]={0};

void ellenoriz(long int x[17][17])
{
 int s=0;
 for (int i=1;i<=n;i++)
	 for (int j=1;j<=m;j++)
		s+=x[i][j];
 if(s>max)
	 max=s;
}

void olvas()
{freopen("flip.in","r",stdin);
 cin>>n>>m;
 max=0;
 for (int i=1;i<=n;i++)
	 for (int j=1;j<=m;j++)
		 {cin>>a[i][j];
		  max+=a[i][j];
		 }
}


void back(int i, int j, long int x[17][17])
{
	
	if(i<=n)
	 back(i+1,j,a);
	else ellenoriz(x);
	
	for(int k=1;k<=m;k++)
		x[i][k]=x[i][k]*-1;
	

	if(j<=m)
	 back(i,j+1,a);
	else  ellenoriz(x);
	
		for(int k=1;k<=n;k++)
		x[k][j]=x[k][j]*-1;
}


int main()
{olvas();
 long int x[17][17];
  for (int i=1;i<=n;i++)
	 for (int j=1;j<=m;j++)
		 x[i][j]=a[i][j];

 back(1,1,x);	
 freopen("flip.out","w",stdin);
 cout<<max;
 return 0;
}