var f,g:text;
    min,l,c,slp,sln,scp,scn,maxc,maxl,i,j,n,m,s:longint;
    a:array[1..16,1..16] of longint;
begin
assign(f,'flip.in');reset(f);
assign(g,'flip.out');rewrite(g);
read(f,n,m);
min:=2000000000;
maxl:=0;
maxc:=0;
for i:=1 to n do begin
    slp:=0;
    sln:=0;
    for j:=1 to m do begin
        read(f,a[i,j]);
        if a[i,j]<0 then sln:=sln+a[i,j]
                    else slp:=a[i,j]+slp;
        end;
    if ((sln*(-1)>slp)or(sln+slp<min))and(sln*(-1)>maxl) then begin
       maxl:=sln*(-1);
       min:=slp+sln;
       l:=i;
       end;
    end;
min:=2000000000;
for i:=1 to m do begin
    scp:=0;
    scn:=0;
    for j:=1 to n do
        if a[j,i]<0 then scn:=scn+a[j,i]
                    else scp:=a[j,i]+scp;
    if ((scn*(-1)>scp)or(scp+scn<min))and(scn*(-1)>maxc) then begin
       maxc:=scn*(-1);
       min:=scp+scn;
       c:=i;
       end;
    end;
s:=0;
for i:=1 to n do
    for j:=1 to m do
        if (a[i,j]<>a[l,c])and((i=l)or(j=c)) then s:=s+a[i,j]*(-1)
                                             else s:=s+a[i,j];
writeln(g,s);
close(f);
close(g);
end.