func_code_string: #include <bits/stdc++.h>   using namespace std;   long long int f(long long int a) {     long long int i, r = 0;     for (i = 1; i <= a; i++) {       r += i * (9 * (pow(10, i - 1)));     }     return r;   }   int main() {     long long int i, n, a;     cin >> n;     for (i = 1; n % (long long int)(pow(10, i)) != n; i++)       ;     a = f(i - 1);     n = n - (pow(10, i - 1));     a = a + ((n + 1) * (i));     cout << a;   }   