#include <cstdio>
#include <algorithm>
#include <iostream>
#include <cmath>
using namespace std;
typedef long long ll;

int N;

int main(int argc, char const *argv[]) {
	cin >> N;
	int d[101];
	d[0] = N % 10;
	int res1 = N / 10;
	int res2;
	for (int i = 99; i >= 10; i--) {
		res2 = i * N + res1;
		d[100-i] = res2 % 100;
		res1 = res2 / 100;
	}
	for (int i = 9; i > 0; i--) {
		res2 = i * N + res1;
		d[100-i] = res2 % 10;
		res1 = res2 / 10;
	}
	cout << res1 << '.';
	for (int i = 99; i >= 0; i--) {
		cout << d[i];
	}
	cout << endl;
	return 0;
}