#include<bits/stdc++.h>
#define int long long
const int mod = 1e9 + 7;
using namespace std;

signed main()
{
	string s;
	cin >> s;
	int cnt = 0;
	for(int i = 0; i < s.size(); i++){
		if(s[i] == '1' || s[i] == '2' || s[i] == '4' || s[i] == '8'){
			cnt++;
		}
	}
	cout << cnt;
	
	return 0;
}