Info

#include <iostream>
#include <fstream>
#include <cstring>
#define NMAX 1000000

using namespace std;

ifstream f("date.in");
ofstream g("date.out");

long long curr = 9, put10 = 1, nr, sum, cr;
char s[NMAX+10];

int main()
{
    f >> s;
    long long nrcif = strlen(s);
    while(sum < nrcif)
        {   sum = sum + (nr + 1) * curr;
            curr = curr * 10;
            nr++;
            put10 = put10 * 10;
        }
    sum = sum - nr * (curr / 10);
    g << (nrcif - sum) / nr + put10 / 10 - 1 << '\n';
    return 0;
}