func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     long long l, r;     cin >> l >> r;     long long x = r, y = 0;     while (x > 0) {       ++y;       x /= 10;     }     x = 5;     long long k = y;     for (int i = 0; i < k - 1; ++i) {       x *= 10;     }     if (r < x)       x = r;     else if (l > x)       x = l;     k = x;     vector<long long> ans;     while (k > 0) {       ans.push_back(k % 10);       k /= 10;     }     reverse(ans.begin(), ans.end());     y = 0;     for (auto& i : ans) {       y *= 10;       y += 9 - i;     }     cout << x * y;     return 0;   }   