program cuv;
var c:char;
cuv:boolean;
nr, nrcuv, medie:longint;
f,g:text;
begin
assign(f,'text.in'); reset(f);
assign(g,'text.out');rewrite(g);
cuv:=false;
while not eof(f) do begin
 read(f,c);
 if ( ((ord(c)>=65)and(ord(c)<=90))or((ord(c)>=97)and(ord(c<=122)) ) and (cuv=false) then  begin
 nr:=nr +1;
 nrcuv:=nrcuv +1;
 cuv:=true;
 end else if ( ((ord(c)>=65)and(ord(c)<=90))or((ord(c)>=97)and(ord(c<=122)) ) and (cuv=true) then nr:=nr+1
 else cuv:=false;
 end;
 medie:=nr/nrcuv;
 write(g,medie);
 close(f); close(g);
 end.