func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     string s;     cin >> s;     unsigned long long ans = 0;     for (int i = 0; i < s.size(); i++) {       int x = s[i] -  0 ;       if (x % 4 == 0) ans++;       if (i > 0) {         x += 10 * (s[i - 1] -  0 );         if (x % 4 == 0) ans += i;       }     }     cout << ans << endl;     return 0;   }   