Pascal :

var
  s:string;
  i,b:integer;
begin
  readln(s);
  i:=0;
  repeat
    inc(i);
    if s[i] in ['A'..'Z'] then
      s[i]:=chr(ord(s[i])+ord('a')-ord('A'))
      else if s[i] in ['a'..'z'] then
        s[i]:=chr(ord('A')+ord(s[i])-ord('a'));
      
  until s[i]='?';
  for i:=1 to length(s)-1 do
    write(s[i])
end.