program tmp;
uses crt;
var x,i,x1,code,k:integer;
st:string;
begin
clrscr;
readln(x);
str(x,st);
k:=0;
for i:=1 to length(st) do begin
val(st[i],x1,code);
if odd(x1) then k:=k+1;
end;
write(k);
readkey;
end.