program flippy;
var f,g:text;
    s:comp;
    a:array[1..16,1..16] of longint;
    n,m,i,y:longint;
    s1,s2:array[1..16] of longint;
    k:boolean;
    begin
assign(f,'flip.in'); reset(f);
assign(g,'flip.out'); rewrite(g);
readln(f,n,m);
for i:=1 to n do
        for y:=1 to m do
                begin
                read(f,a[i,y]);
                s1[i]:=s1[i]+a[i,y];
                s2[y]:=s2[y]+a[i,y];
                end;
repeat
k:=false;
for i:=1 to n do
        if s1[i]<0 then
                begin
                for y:=1 to m do
                        begin
                        a[i,y]:=-1*a[i,y];
                        s2[y]:=s2[y]+2*a[i,y];
                        end;
                s1[i]:=-1*s1[i];
                k:=true;
                end;
for i:=1 to m do
        if s2[i]<0 then
                begin
                for y:=1 to n do
                        begin
                        a[y,i]:=-1*a[y,i];
                        s1[y]:=s1[y]+2*a[y,i];
                        end;
                s2[i]:=-1*s2[i];
                k:=true;
                end;
until k=false;
for i:=1 to n do
        s:=s+s1[i];
writeln(g,s:0:0);
close(f); close(g);
end.