#include<iostream>
#include <string>
#include <sstream>

using namespace std;

int main()
{
	int number;
	cin >> number;
	double sumOne = number * 0.7;
	double sumTwo = sumOne * 0.85;
	double sumThree = sumTwo / 2;
	cout.setf(ios::fixed);
	cout.precision(2);
	cout << sumOne + sumTwo + sumThree + number << endl;

	return 0;
}