#include<stdio.h>


FILE *f,*g;

void linie(int v[100][100],int l,int c)
{
int i,sn=0,sp=0;

for(i=0;i<c;i++)
    {
    if(v[l][i]>0)sp=sp+v[l][i];
        else sn=sn-v[l][i];
    }

if(sn>sp){
    for(i=0;i<c;i++){
        v[l][i]=(-1)*v[l][i];}}

}

void coloana(int v[100][100],int l,int c)
{
int i,sn=0,sp=0;

for(i=0;i<l;i++)
    {
    if(v[i][c]>0)sp=sp+v[i][c];
        else sn=sn-v[i][c];
    }

if(sn>sp){
    for(i=0;i<l;i++){
        v[i][c]=(-1)*v[i][c];}}

}




void main ()
{
int n,m,i,j,v[100][100],s=0;


f=fopen("filip.in","r");
fscanf(f,"%d%d",&n,&m);
for(i=0;i<n;i++){
    for(j=0;j<m;j++){
        fscanf(f,"%d",&v[i][j]);}}
fclose(f);


for(i=0;i<n;i++){linie(v,i,m);}
for(i=0;i<m;i++){coloana(v,n,i);}

for(i=0;i<n;i++){
    for(j=0;j<m;j++){
        s=s+v[i][j];}}

g=fopen("filip.out","w");
fprintf(g,"%d",s);
fclose(g);

}