#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

string to_str(ll x) {
	stringstream ss;
	ss << x;
	return ss.str();
}

int main() {
	ll d;
	cin >> d;
	
	ll p = d * 8;
	
	string f = to_str(p);
	f = "000" + f;
	f = f.substr(f.size() - 2, 2);
	
	printf("%lld.%s\n", d + p / 100, f.c_str());
	return 0;
}