const separatori=[' ',',','!','?','.',';','(',')','[',']','-','_'];
var s:string;
    i,nr,nrl:integer;
    f:text;
begin
     assign(f,'text.in');
     reset(f);
     read(f,s);
     close(f);
     nr:=1;
     For i:=1 to length(s) Do
         begin
         IF not (s[i] in separatori) THEN
         nrl:=nrl+1 else
         IF not (s[i-1] in separatori) THEN
         nr:=nr+1;
         end;
     assign(f,'text.out');
     rewrite(f);
     writeln(f,nrl/nr:0:2);
     close(f);
end.