Program enot;
Var s:string;
a:char;
b,n,h,i:integer;
l:real;
begin
read(s);
n:= length(s);
h:=0;
for i:= 1 to n do
case s[i] of
'ы': h:=h+1;
'у':h:=h+1;
'е':h:=h+1;
'и':h:=h+1;
'а':h:=h+1;
'о':h:=h+1;
'ё':h:=h+1;
'э':h:=h+1;
'ю':h:=h+1;
'я':h:=h+1;
end;b:=n-h;
l:=b/n;
writeln(l:4:2);
end.