var a:char; s:string; f,g:text; k,cl,cc:longint; v:array[1..52] of char;
procedure generare_vector;
var i:char;
begin
 k:=0;
 for i:='a' to 'z' do
 begin
 k:=k+1;
 v[k]:=i;
 begin
 k:=k+1;
 v[k]:=i;
 end;
end;
end;

 function find(x:char):boolean;
var i:integer;
   ok:boolean;
 begin
 ok:=false;
 i:=1;
 while (ok=false) and (i<=k) do
 begin
 if v[i]=x then
 ok:=true;
 i:=i+1;
 end;
 find:=ok;
 end;

BEGIN
assign(f,'text.in'); reset(f);
assign(g,'text.out'); rewrite(g);
generare_vector;
cl:=0;
cc:=0;
while not eof(f) do
 begin
 s:='';
 while find(a) do
  begin
   s:=s+a;
   cl:=cl+1;
   read(f,a);
  end;
 if (not find(a)) and (s<>'') then cc:=cc+1
 end;
 write(g, trunc(cl/cc));
 close(f); close(g);
 end.