func_code_string: #include <bits/stdc++.h>   using namespace std;   long long int l, r, sum = 0, tempVariable, doneTillHereInArrayOfNumbers = 3;   long long int arrayOfNumbers[100000];   long long int createNextLuckyNumber() {     if (doneTillHereInArrayOfNumbers % 2 == 0) {       arrayOfNumbers[doneTillHereInArrayOfNumbers] =           (arrayOfNumbers[doneTillHereInArrayOfNumbers / 2 - 1] * 10) + 7;     } else {       arrayOfNumbers[doneTillHereInArrayOfNumbers] =           (arrayOfNumbers[doneTillHereInArrayOfNumbers / 2] * 10) + 4;     }     return arrayOfNumbers[doneTillHereInArrayOfNumbers++];   }   long long int FirstLuckyNumberGreaterThanOrEqualToL() {     if (4 < l) {       goto down;     }     if (4 >= l && 4 <= r) {       sum += 4 * (4 - l + 1);       l = 5;     } else if (4 >= l && 4 > r) {       sum += 4 * (r - l + 1);       l = r;       cout << sum;       exit(0);     }   down:     if (7 < l) {       goto down2;     }     if (7 >= l && 7 <= r) {       sum += 7 * (7 - l + 1);       l = 8;     } else if (7 >= l && 7 > r) {       sum += 7 * (r - l + 1);       cout << sum;       exit(0);     }   down2:     long long int num = 0;     while (num < l) {       num = createNextLuckyNumber();     }     return num;   }   int main() {     cin >> l >> r;     arrayOfNumbers[1] = 4;     arrayOfNumbers[2] = 7;     tempVariable = FirstLuckyNumberGreaterThanOrEqualToL();     if (tempVariable <= r) {       sum += tempVariable * (tempVariable - l + 1);       l = tempVariable;     } else {       sum += tempVariable * (r - l + 1);       cout << sum;       exit(0);     }     l++;     while (l <= r) {       tempVariable = createNextLuckyNumber();       if (tempVariable <= r) {         sum += tempVariable * (tempVariable - l + 1);         l = tempVariable;       } else {         sum += tempVariable * (r - l + 1);         break;       }       l++;     }     cout << sum;     return 0;   }   