include <bits/stdc++.h>

using namespace std;

int main() {

int n;
cin >> n;
int count = 0;
for (int i = 0; i < 5; ++i) {
	int digit = n % 10;
	if (digit % 2 == 0) {
		++count;
	}
	n /= 10;
}
cout << count ;
return 0;

}