#include <bits/stdc++.h>
using namespace std;
string func(int x, int l) {
	string s = to_string(x);
	while(s.size() < l) s = '0' + s;
	return s;
}
long long x;
int main() {
	cin >> x;
	long long q = x * 8;
	x += q / 100, q %= 100;
	cout << x << '.' << func(q, 2) << endl;
	return 0;
}