#include<fstream.h>
ifstream f("flip.in");
ofstream g("flip.out");
long a[17],b[17];
int main()
{ long long S;
    int j,i,n,m;

  f>>n>>m; for(i=1;i<=n;i++) 
               for(j=1;j<=m;j++) { f>>S;a[i]+=S;b[j]+=S;
                                 } S=0;
   for(i=1;i<=n;i++) { if(a[i]>0)S+=a[i];else S-=a[i];} 
   for(i=1;i<=n;i++) { if(b[i]<0)S-=2*b[i];
                     }
                     g<<S;return 0;                     
}