#include<stdio.h>
long int a[17][17],v[17],o[17],s;
int m,n,i,j,ok;
int main()
{
FILE *f;
f=fopen("flip.in","r");
fscanf(f,"%d%d",&n,&m);
for(i=1;i<=n;i++)
for(j=1;j<=m;j++)
{fscanf(f,"%ld",&a[i][j]);
o[i]+=a[i][j];
v[j]+=a[i][j];}
fclose(f);
ok=1;
while(ok)
{ok=0;
	for(i=1;i<=n;i++)
	{if(o[i]<0)
		{ok=1;
		o[i]=-o[i];
		for(j=1;j<=m;j++)
		{a[i][j]=-a[i][j];v[j]+=2*a[i][j];}
		}
	}
	for(i=1;i<=m;i++)
	{if(v[i]<0)
		{ok=1;
		v[i]=-v[i];
		for(j=1;j<=n;j++)
		{a[j][i]=-a[j][i];o[i]+=2*a[i][j];}
		}
	}
}
for(i=1;i<=n;i++) s+=o[i];
f=fopen("flip.out","W");
fprintf(f,"%ld\n",s);
fclose(f);
return 0;
}