var a:array[1..255]of int64;
    s:int64;
procedure init;
var i:byte;
begin
 for i:=1 to 255 do a[i]:=0;
end;

procedure citire;
var c:char;f:text;
begin
 assign(f,'text.in');
 reset(f);
 while not eof(f) do
  begin
   read(f,c);
   inc(a[ord(c)]);
  end;
 close(f);
end;

procedure calc;
var i:byte;
begin
 s:=0;
 for i:=65 to 90 do s:=s+a[i];
 for i:=97 to 122 do s:=s+a[i];
end;

procedure afis;
var f:text;
begin
 assign(f,'text.out');
 rewrite(f);
 writeln(f,s/a[32]);
 close(f);
end;

begin
 init;
 citire;
 calc;
 afis;
end.