var a:array[1..20,1..20]of longint;
    b:array[1..400]of qword;
    n,m,i,j,l,k,q:longint;
    max:qword;
    f,g:text;
begin
assign(f,'flip.in');reset(f);
assign(g,'flip.out');rewrite(g);
read(f,n,m);
l:=0;
for i:=1 to n do
    for j:=1 to m do
        begin
        inc(l);
        b[l]:=0;
        for k:=1 to n do
            b[l]:=b[l]-a[k,j];
        for k:=1 to m do
            b[l]:=b[l]-a[i,k];
        b[l]:=b[l]+a[i,j];
        for k:=1 to n do
            for q:=1 to m do
                if (i<>k)or(q<>j) then b[l]:=a[i,j];
        end;
max:=b[1];
for i:=1 to l do
    if b[i]>max then max:=b[i];
writeln(g,max);
close(f);
close(g);
end.