#include <iostream>
#include <cstdio>
#include <vector>
#include <algorithm>
#include <utility>
#include <string>

using namespace std;

int main() {
	string D = "1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
	int n;
	cin >> n;
	int nd = D.size();

	vector<int> d(nd, 0);
	for (int i = 0; i < nd; i++) {
		d[i] = D[i] - '0';
	}

	int to = 0;
	for (int i = nd - 1; i >= 0; i--) {
		d[i] = d[i] * n + to;
		to = d[i] / 10;
		d[i] %= 10;
	}

	cout << to << ".";
	for (auto e : d) {
		cout << e;
	}
	cout << endl;

	return 0;
}