dsad

#include <iostream>
#include <iomanip>

using namespace std;



int main() {

    int a,sum = 0, b;
    cin >> a;
    while (a>0) {
        b = a % 10;
        if (b%2==0) {
            sum++;
        }
        a /= 10;
    }
    cout << sum;

    system("pause");
    return 0;
}