#include<fstream.h>

ifstream f("flip.in");
ofstream o("flip.out");
int main(){int a,b,m[16][16],i,j,s,v[20],n,sw=0,w[20],c1,c2,poz1,poz2;
f>>a>>b;
for(i=1;i<=a;i++)for(j=1;j<=b;j++)f>>m[i][j];
do{{if(sw==1)
{if((c1<0)&&(c1<c2))for(i=1;i<=a;i++)m[poz1][i]=-m[poz1][i];
if((c2<0)&&(c2<c1))for(i=1;i<=b;i++)m[i][poz2]=-m[i][poz2];}}
for(i=1;i<=b;i++){s=0;{for(j=1;j<=a;j++)s=s+m[i][j];}v[i]=s;}
for(i=1;i<=a;i++){s=0;{for(j=1;j<=b;j++)s=s+m[i][j];}w[i]=s;}
c1=v[1];
for(i=1;i<=b;i++)if(v[i]<c1){c1=v[i];poz1=i;}
c2=w[1];
for(i=1;i<=a;i++)if(w[i]<c2){c2=w[i];poz2=i;}
sw=1;
}while((c1>0)||(c2>0));


s=0;
for(i=1;i<=a;i++)for(j=1;j<=b;j++)s=s+m[i][j];
o<<s;
return 0;
}