func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int t = 1;     while (t--) {       long long l, r, i, sum = 0;       deque<long long> a;       a.push_back(4);       a.push_back(7);       cin >> l >> r;       for (i = l; i <= r;) {         if (i <= a.front()) {           sum += a.front();           i++;         } else {           a.push_back(a.front() * 10 + 4);           a.push_back(a.front() * 10 + 7);           a.pop_front();         }       }       cout << sum <<    ;     }     return 0;   }   