# include <stdio.h>   
long int s,s1,s2,s3,s4,i,j,n,m,k,a[20][20],p;   
int main ()   
{   
freopen ("flip.in","r",stdin);   
freopen ("flip.out","w",stdout);   
scanf ("%li",&n);   
scanf ("%li",&m);   
for (i=0;i<n;i++)   
for (j=0;j<m;j++)   
scanf ("%li",&a[i][j]);   
for (p=0;p<10;p++)   
{   
for (i=0;i<n;i++)   
for (j=0;j<m;j++)   
{   
s1=0;   
s2=0;   
s3=0;   
s4=0;   
if (a[i][j]<0)   
{   
for (k=0;k<m;k++)   
{   
s1=s1+a[i][k];   
s2=s2+(a[i][k]*-1);   
}   
for (k=0;k<n;k++)   
{   
s3=s3+a[k][j];   
s4=s4+(a[k][j]*-1);   
}   
if (s2>s1 && s4<s3)   
{   
for (k=0;k<m;k++)   
a[i][k]=a[i][k]*-1;   
}   
if (s2<s1 && s4>s3)   
{   
for (k=0;k<n;k++)   
a[k][j]=a[k][j]*-1;   
}   
if (s2>s1 && s4>s3)   
if (s2>s4)   
for (k=0;k<m;k++)   
a[i][k]=a[i][k]*-1;   
else  
for (k=0;k<n;k++)   
a[k][j]=a[k][j]*-1;   
}   
}   
}   
for (i=0;i<n;i++)   
for (j=0;j<m;j++)   
s=s+a[i][j];   
printf ("%li",s);   
return 0;   
}