program flip;
var f:text;
    n,m,i,j,o:longint;
    t:array[1..16,1..16] of longint;

procedure row(r:word);
var i,op,on:longint;
begin
     op:=0;on:=0;
     for i:=1 to m do
     begin
          if(t[r,i] > 0) then inc(op,t[r,i])
          else inc(on,t[r,i]);
     end;
     if((-1)*on > op) then
     begin
          for i:=1 to m do
              t[r,i]:=(-1)*t[r,i];
     end;
end;

procedure col(c:word);
var i,op,on:longint;
begin
     op:=0;on:=0;
     for i:=1 to n do
     begin
          if(t[i,c] > 0) then inc(op,t[i,c])
          else inc(on,t[i,c]);
     end;
     if((-1)*on > op) then
     begin
          for i:=1 to n do
              t[i,c]:=(-1)*t[i,c];
     end;
end;

begin
     assign(f,'flip.in');
     reset(f);
     readln(f,n,m);
     for i:=1 to n do
     begin
          for j:=1 to m do
              read(f,t[i,j]);
          readln(f);
     end;
     close(f);

     for i:=1 to n do
         row(i);
     for i:=1 to m do
         col(i);
     o:=0;
     for i:=1 to n do
         for j:=1 to m do
              inc(o,t[i,j]);

     assign(f,'flip.out');
     rewrite(f);
     write(f,o);
     close(f);
end.