Untitled

import java.util.Scanner;

public class P1 {
	public static int Sol(int n) {
		int cnt = 0;
		while (n != 0) {
			if (n % 10 % 2 == 1) {
				cnt++;
			}
			n /= 10;
		}

		return cnt;
	}

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = sc.nextInt();

		System.out.println(Sol(n));
//		Sol(n);

	}
}