#include<stdio.h>
#include<stdlib.h>
#include<math.h>
int main()
{
FILE *f,*g;
int p,max,n,m,i,j,k,s1,a[18][18];
f=fopen("flip.in","r");	
g=fopen("flip.out","w");
fscanf(f,"%d",&n);
fscanf(f,"%d",&m);

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

for (i=1;i<=m;i++)
{
s1=0; 
for (j=1;j<=n;j++) s1=s1+a[j][i];
if (s1<=0) {for (k=1;k<=n;k++) a[k][i]=a[k][i]*-1;}
}

for (i=1;i<=n;i++)
{
s1=0; 
for (j=1;j<=m;j++) s1=s1+a[i][j];
if (s1<0) {for (k=1;k<=m;k++) a[i][k]=a[i][k]*-1;}
}


max=0;
for (i=1;i<=n;i++)
for (j=1;j<=m;j++)
max=max+a[i][j];	
max=abs(max);
fprintf(g,"%d",max);
fclose(f);
fclose(g);
return 0;
}