include <bits/stdc++.h>

using namespace std;

int main() {

int n, a = 0, b = 0, c = 0, d = 0, e = 0, sum = 0;
cin >> n;
a = n % 10;
b = n / 10 % 10;
c = n / 100 % 10;
d = n / 1000 % 10;
e = n / 10000 % 10;
if (a % 2 == 0) {
	sum++;
}
if (b % 2 == 0) {
	sum++;
}
if (c % 2 == 0) {
	sum++;
}
if (d % 2 == 0) {
	sum++;
}
if (e % 2 == 0) {
	sum++;
}
cout << sum;
return 0;

}