Program POpPP;
var t:array[1..16,1..16] of longint;
    i,n,m,j:integer;
    plus,minus,suma:longint;
begin
assign(input,'flip.in');
reset(input);
readln(n,m);
for i:=1 to n do
begin
for j:=1 to m do
read(t[i,j]);
readln;
end;
close(input);
for i:=1 to n do
        begin
                plus:=0;
                minus:=0;
                for j:=1 to m do
                        begin
                                plus:=plus+t[i,j];
                                minus:=minus+t[i,j]*(-1);
                        end;
                if minus>plus then
                for j:=1 to m do
                t[i,j]:=-1*t[i,j];
        end;
for j:=1 to m do
        begin
                plus:=0;
                minus:=0;
                for i:=1 to n do
                        begin
                                plus:=plus+t[i,j];
                                minus:=minus+t[i,j]*(-1);
                        end;
                if minus>plus then
                for i:=1 to n do
                t[i,j]:=-1*t[i,j];
        end;
suma:=0;
for i:=1 to n do
for j:=1 to m do
suma:=suma+t[i,j];
writeln(suma);
end.