#include<fstream.h>
int c[17],l[17],i,j,ap,k,k2,m,n,s,si,st,min,negativ,a[17][17];
int main()
{
ifstream in("flip.in");
ofstream out("flip.out");
in>>m;
in>>n;
ap=0;
for(i=1;i<=m;i=i+1)
for(j=1;j<=n;j=j+1)
{in>>a[i][j];
 l[i]=l[i]+a[i][j];
 c[j]=c[j]+a[i][j];
 si=si+a[i][j];
}
min=l[1];
for(i=2;i<=m;i=i+1)
if(l[i]<min) min=l[i];
for(j=1;j<=n;j=j+1)
if(c[j]<min) {min=c[j];
	      ap=1;
	     }

if(ap==0)

{ negativ=1;
  do
{for(i=1;i<=m;i=i+1)
 if(l[i]<0)
       {l[i]=0;
       for(j=1;j<=n;j=j+1)
	   { a[i][j]=-a[i][j];
	   l[i]=l[i]+a[i][j];
	   c[j]=c[j]+2*a[i][j];
	   }
	st=st+l[i];
       }
       else st=st+l[i];
if(si<st) si=st;
st=0;


for(j=1;j<=n;j=j+1)
if(c[j]<0)
       {negativ=0;
	c[j]=0;
	for(i=1;i<=m;i=i+1)
	   { a[i][j]=-a[i][j];
	   c[j]=c[j]+a[i][j];
	   l[i]=l[i]+2*a[i][j];
	   if(l[i]<0) negativ=1;
	   }
	st=st+c[j];
	}
   else {st=st+c[j];
	 negativ=0;
	}
if(si<st) si=st;
st=0;
}while(negativ==1);
}

else
{negativ=1;
do
{for(j=1;j<=n;j=j+1)
if(c[j]<0)
       {negativ=0;
	c[j]=0;
	for(i=1;i<=m;i=i+1)
	   { a[i][j]=-a[i][j];
	   c[j]=c[j]+a[i][j];
	   l[i]=l[i]+2*a[i][j];
	   if(l[i]<0) negativ=1;
	   }
	st=st+c[j];
	}
   else {st=st+c[j];
	 negativ=0;
	}
if(si<st) si=st;
st=0;

for(i=1;i<=m;i=i+1)
if(l[i]<0)
       {l[i]=0;
       for(j=1;j<=n;j=j+1)
	   { a[i][j]=-a[i][j];
	   l[i]=l[i]+a[i][j];
	   c[j]=c[j]+2*a[i][j];
	   }
	st=st+l[i];
       }
       else st=st+l[i];

if(si<st) si=st;
st=0;
}while(negativ==1);
}
s=0;
for(i=1;i<=m;i=i+1)
s=s+l[i];
if(si>s) out<<si;
       else  out<<s;
in.close();
out.close();
return 0;
}