var
n,m,s1,s2,i,j,s:longint;
f,g:text;
slin,scol:array[1..100]of longint;
a:array[1..20,1..20]of longint;
begin
        assign(f,'flip.in');reset(f);
        assign(g,'flip.out');rewrite(g);
        readln(f,n,m);
        for i:=1 to n do
                for j:=1 to m do
                        read(f,a[i,j]);
        for i:=1 to m do begin
                s1:=0;
                s2:=0;
                for j:=1 to n do
                        s1:=s1+a[j,i];
                for j:=1 to n do
                        s2:=s2+a[j,i]*-1;
                if s1<s2 then for j:=1 to n do a[j,i]:=a[j,i]*-1;
        end;
        for i:=1 to n do begin
                s1:=0;
                s2:=0;
                for j:=1 to m do
                        s1:=s1+a[i,j];
                for j:=1 to m do
                        s2:=s2+a[i,j]*-1;
                if s1<s2 then for j:=1 to m 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];
        writeln(g,s);
        close(f);
        close(g);
end.