var f,g:text;
con,suma,lcuv:qword;
{cuv:String;}
c:char;
{rez:qword;}
begin
assign (f,'text.in');
assign(g,'text.out');
reset(f);
rewrite(g);
suma:=0;  con:=0;
while not eof(f) do begin
while not eoln(f) do begin
read(f,c);
if c in ['a'..'z','A'..'Z'] then inc(lcuv){cuv:=cuv+c}
else begin
      if ({cuv<>''}lcuv<>0) then   begin
        suma:=suma+{length(cuv)}lcuv;
        inc(con); end;
{cuv :=''}lcuv:=0;
 end;
end;
if ({cuv<>''}lcuv<>0) then begin
suma:=suma+{length(cuv)}lcuv;
inc(con);
end;
readln(f);
end;
if con<>0 then write(g,suma div con) else write(g,0);
close(g);
end.