{*****************}
{*}Program flip;{*}
{*****************}

{****} Var a:array[1..16,1..16] of -1000000..1000000;
           f:text;
           s:longint;
           n,m,i,j:1..16;

{*}Begin{*}
assign(f,'flip.in');reset(f);
read(f,n,m);
for i:=1 to n do
        for j:=1 to m do
                read(f,a[i,j]);
close(f);
for i:=1 to n do begin
         s:=0;
         for j:=1 to m do
             if a[i,j]<-a[i,j] then s:=s+2*(-a[i,j])
                               else s:=s-2*a[i,j];
         if s>0 then for j:=1 to m do a[i,j]:=a[i,j]*(-1);
         end;
for j:=1 to m do begin
         s:=0;
         for i:=1 to n do
             if a[i,j]<-a[i,j] then s:=s+2*(-a[i,j])
                               else s:=s-2*a[i,j];
         if s>0 then for i:=1 to n do a[i,j]:=a[i,j]*(-1);
         end;
s:=0;
for i:=1 to n do
        for j:=1 to m do
                s:=s+a[i,j];
assign(f,'flip.out');rewrite(f);
write(f,s);close(f);
{*}End.{*}