func_code_string: #include <bits/stdc++.h>   int main(int argc, char *argv[]) {     int i, j;     unsigned long long n, result, a[10];     a[0] = 0;     a[1] = 9;     for (i = 2; i <= 9; i++) a[i] = a[i - 1] * 10 + 9;     scanf( %llu , &n);     result = 0;     i = 9;     ;     while (n < a[i]) i--;     result = result + (n - a[i]) * (i + 1);     for (j = 1; j <= i; j++) result = result + (a[j] - a[j - 1]) * j;     printf( %llu , result);     return 0;   }   