program de;
    var
    a,b:array[-1400..1400] of integer;
    a1,b1:array[1..2800] of integer;
    i,j,n,max_a,max_b:integer;
    ch:char;
procedure diog;
begin
        if ch='s' then
            begin
             b[i-j]:=0;
             inc(a[i-j]);
             if a[i-j]>max_a then max_a:=a[i-j];
            end
         else
           begin
             a[i-j]:=0;
             inc(b[i-j]);
             if b[i-j]>max_b then max_b:=b[i-j];
            end;
end;
procedure diogobrat;
begin
        if ch='s' then
            begin
             b1[i+j]:=0;
             inc(a1[i+j]);
             if a1[i+j]>max_a then max_a:=a1[i+j];
            end
         else
           begin
             a1[i+j]:=0;
             inc(b1[i+j]);
             if b1[i+j]>max_b then max_b:=b1[i+j];
            end;
end;
procedure vivod;
begin
   if max_a=max_b then
      begin
        writeln('?');
        writeln(max_a);
      end
   else
   if max_a<max_b then
      begin
        writeln('S');
        writeln(max_b);
      end
   else
      begin
        writeln('s');
        writeln(max_a);
      end;
end;
begin
{   assign(input,'c:\test.txt');
   reset(input);                   }
   readln(n);
   for i:=1 to n do
   begin
     for j:=1 to n do
      begin
        read(ch);
        diog;
        diogobrat;
      end;
      readln;
   end;
   vivod;
end.

There is test where your program wrongs:
5
sSSSS
SSsss
ssSSS
sSSss
sSSSS
Your program outputs
?
3
but real answer is obvious
S
4
Good luck!

I thought what to consider it is necessary only on a diagonal.
Thanks, now I have AC.

Thank you for this test and thanks to my friend Agabek.
I got AC now.

Exactly! Do NOT forget to consider vertical and horizontal arrays.