program test4;
const max=20;
var a,b:array[1..max] of integer;
n:string; len,i,j,s:integer;
begin
readln(n);
len:=length(n);
i:=len; j:=1;
while i>0 do
begin
a[j]:=ord(n[i])-ord ('0') ;
inc (j) ; dec (i) ;
end;
s:=0;
for i:=1 to len do
if a[i]>=5 then inc(s) ;
writeln (s) ;
end.
输入: 387543284570123
输出：6