#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
using namespace std;
int main()
{
    int n;
    cin >> n;
    n < 5 ? cout << fixed << setprecision(0) << (pow(10.0f, n) - pow(10.0f, n - 1)) * (pow(10.0f, n - 1) + (pow(10.0f, n) - 1)) / 2 << endl : cout << "4949" << string(n - 4, '9') << "55" << string(n - 2, '0') << endl;
    return 0;
}