#include<fstream.h>
int main()
{
int l,c,i,j,s1,s2,s3,a[20][20];
ifstream in("flip.in");
ofstream out("flip.out");
in>>l>>c;

for(i=1;i<=l;i++)
for(j=1;j<=c;j++)
in>>a[i][j];

for(j=1;j<=c;j++)
{
s1=s2=0;

for(i=1;i<=l;i++)
{
s1=s1+a[i][j];
s2=s2+a[i][j]*-1;
};

if(s2>s1)

for(i=1;i<=l;i++)
{
a[i][j]=a[i][j]*-1;
};

};

for(i=1;i<=l;i++)
{
s1=s2=0;
for(j=1;j<=c;j++)
{
s1=s1+a[i][j];
s2=s2+a[i][j]*-1;
};
if(s2>s1)

for(j=1;j<=c;j++)
{
a[i][j]=a[i][j]*-1;
};
};

s3=0;

for(i=1;i<=l;i++)
for(j=1;j<=c;j++)
s3+=a[i][j];
out<<s3;
}