uses crt;
var f:text;
    a:array[1..17,1..17] of longint;
    n,m,i,j,s:longint;
begin
 clrscr;
 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);
 s:=0;
 for i:=1 to n do
   begin
     for j:=1 to m do
         s:=s+a[i,j];
     if s<0 then for j:=1 to m do
                     a[i,j]:=a[i,j]*(-1);
     s:=0;
   end;
 for j:=1 to m do
   begin
     for i:=1 to n do
         s:=s+a[i,j];
     if s<0 then for i:=1 to n do
                     a[i,j]:=a[i,j]*(-1);
     s:=0;
   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.