const m:set of char=['a'..'z','A'..'Z'];
var a,b,nr,s:longint;
c:char;
f,g:text;
begin
assign(f,'text.in');reset(f);
assign(g,'text.out');rewrite(g);
a:=-1;
b:=-1;
s:=0;
nr:=0;
while not eof(f) do begin
read(f,c);
if c in m then
if a=-1 then begin
a:=0;
b:=0;
end
       else b:=b+1
           else if a<>-1 then begin
                           s:=s+b-a+1;
                           nr:=nr+1;
                              end;
end;
if a<>-1 then begin
s:=s+b-a+1;
inc(nr);
end;
writeln(g,s div nr);
close(f);
close(g);
end.