#include <stdio.h>
FILE *f,*g;
int j,i,s=0,s1=0,v[16][16],n,m;
int main() {
f=fopen("flip.in" , "r");
g=fopen("flip.out" , "w");
fscanf(f, "%d" , &n);
fscanf(f, "%d" , &m);
for (i=1; i<=n; i++) 
		for(j=1;j<=m;j++) fscanf(f, "%d" , &v[i][j]);
for(i=1;i<=n; i++) { s1=0;
		for(j=1;j<=m;j++) s1+=v[i][j];
		if(-s1>s1) for(j=1; j<=m; j++) v[i][j]=-v[i][j]; }
for(j=1;j<=m;j++) { s1=0;
		for(i=1; i<=n;i++) s1+=v[i][j];
		if(-s1>s1) for(i=1;i<=n;i++) v[i][j]=-v[i][j];}	 
for(i=1; i<=n; i++)
		for(j=1;j<=m;j++) s+=v[i][j];
fprintf(g, "%d\n" , s);
fclose(f);
fclose(g);
return(0);
}