#include <bits/stdc++.h>   using namespace std;   int main() {     string s;     cin >> s;     long long answer = 0;     for (int i = s.length() - 1; i > 0; i--) {       string temp = s.substr(i - 1, 2);       if (stoi(temp) % 4 == 0) {         answer += i;       }     }     for (int i = 0; i < s.length(); i++) {       if (stoi(s.substr(i, 1)) % 4 == 0) {         answer++;       }     }     cout << answer;   }   