#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<iostream>
#include<string>
#include<cstdio>
#include<vector>
#include<cmath>
#include<algorithm>
#include<functional>
#include<iomanip>
#include<queue>
#include<ciso646>
#include<random>
#include<map>
#include<set>
#include<bitset>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<cassert>
#include<complex>
#include<numeric>
#include<array>
#include<chrono>
using namespace std;

//#define int long long
typedef long long ll;

typedef unsigned long long ul;
typedef unsigned int ui;
//constexpr ll mod = 998244353;
constexpr ll mod = 1000000007;
const ll INF = mod * mod;
typedef pair<int, int>P;

#define rep(i,n) for(int i=0;i<n;i++)
#define per(i,n) for(int i=n-1;i>=0;i--)
#define Rep(i,sta,n) for(int i=sta;i<n;i++)
#define rep1(i,n) for(int i=1;i<=n;i++)
#define per1(i,n) for(int i=n;i>=1;i--)
#define Rep1(i,sta,n) for(int i=sta;i<=n;i++)
#define all(v) (v).begin(),(v).end()
typedef pair<ll, ll> LP;

template<typename T>
void chmin(T& a, T b) {
	a = min(a, b);
}
template<typename T>
void chmax(T& a, T b) {
	a = max(a, b);
}
template<typename T>
void cinarray(vector<T>& v) {
	rep(i, v.size())cin >> v[i];
}
template<typename T>
void coutarray(vector<T>& v) {
	rep(i, v.size()) {
		if (i > 0)cout << " "; cout << v[i];
	}
	cout << "\n";
}
ll mod_pow(ll x, ll n, ll m = mod) {
	if (n < 0) {
		ll res = mod_pow(x, -n, m);
		return mod_pow(res, m - 2, m);
	}
	if (abs(x) >= m)x %= m;
	if (x < 0)x += m;
	//if (x == 0)return 0;
	ll res = 1;
	while (n) {
		if (n & 1)res = res * x % m;
		x = x * x % m; n >>= 1;
	}
	return res;
}
//mod should be <2^31
struct modint {
	int n;
	modint() :n(0) { ; }
	modint(ll m) {
		if (m < 0 || mod <= m) {
			m %= mod; if (m < 0)m += mod;
		}
		n = m;
	}
	operator int() { return n; }
};
bool operator==(modint a, modint b) { return a.n == b.n; }
bool operator<(modint a, modint b) { return a.n < b.n; }
modint operator+=(modint& a, modint b) { a.n += b.n; if (a.n >= mod)a.n -= (int)mod; return a; }
modint operator-=(modint& a, modint b) { a.n -= b.n; if (a.n < 0)a.n += (int)mod; return a; }
modint operator*=(modint& a, modint b) { a.n = ((ll)a.n * b.n) % mod; return a; }
modint operator+(modint a, modint b) { return a += b; }
modint operator-(modint a, modint b) { return a -= b; }
modint operator*(modint a, modint b) { return a *= b; }
modint operator^(modint a, ll n) {
	if (n == 0)return modint(1);
	modint res = (a * a) ^ (n / 2);
	if (n % 2)res = res * a;
	return res;
}

ll inv(ll a, ll p) {
	return (a == 1 ? 1 : (1 - p * inv(p % a, a)) / a + p);
}
modint operator/(modint a, modint b) { return a * modint(inv(b, mod)); }
modint operator/=(modint& a, modint b) { a = a / b; return a; }
const int max_n = 1 << 21;
modint fact[max_n], factinv[max_n];
void init_f() {
	fact[0] = modint(1);
	for (int i = 0; i < max_n - 1; i++) {
		fact[i + 1] = fact[i] * modint(i + 1);
	}
	factinv[max_n - 1] = modint(1) / fact[max_n - 1];
	for (int i = max_n - 2; i >= 0; i--) {
		factinv[i] = factinv[i + 1] * modint(i + 1);
	}
}
modint comb(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[b] * factinv[a - b];
}
modint combP(int a, int b) {
	if (a < 0 || b < 0 || a < b)return 0;
	return fact[a] * factinv[a - b];
}

ll gcd(ll a, ll b) {
	a = abs(a); b = abs(b);
	if (a < b)swap(a, b);
	while (b) {
		ll r = a % b; a = b; b = r;
	}
	return a;
}
using ld = long double;
//typedef long double ld;
typedef pair<ld, ld> LDP;
const ld eps = 1e-10;
const ld pi = acosl(-1.0);
template<typename T>
void addv(vector<T>& v, int loc, T val) {
	if (loc >= v.size())v.resize(loc + 1, 0);
	v[loc] += val;
}
/*const int mn = 2000005;
bool isp[mn];
vector<int> ps;
void init() {
	fill(isp + 2, isp + mn, true);
	for (int i = 2; i < mn; i++) {
		if (!isp[i])continue;
		ps.push_back(i);
		for (int j = 2 * i; j < mn; j += i) {
			isp[j] = false;
		}
	}
}*/

//[,val)
template<typename T>
auto prev_itr(set<T>& st, T val) {
	auto res = st.lower_bound(val);
	if (res == st.begin())return st.end();
	res--; return res;
}

//[val,)
template<typename T>
auto next_itr(set<T>& st, T val) {
	auto res = st.lower_bound(val);
	return res;
}
using mP = pair<modint, modint>;
mP operator+(mP a, mP b) {
	return { a.first + b.first,a.second + b.second };
}
mP operator+=(mP& a, mP b) {
	a = a + b; return a;
}
mP operator-(mP a, mP b) {
	return { a.first - b.first,a.second - b.second };
}
mP operator-=(mP& a, mP b) {
	a = a - b; return a;
}
LP operator+(LP a, LP b) {
	return { a.first + b.first,a.second + b.second };
}
LP operator+=(LP& a, LP b) {
	a = a + b; return a;
}
LP operator-(LP a, LP b) {
	return { a.first - b.first,a.second - b.second };
}
LP operator-=(LP& a, LP b) {
	a = a - b; return a;
}

mt19937 mt(time(0));

const string drul = "DRUL";
string senw = "SENW";
//DRUL,or SENW
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };
//-----------------------------------------
struct bigint {
	string s;
	bigint() {};
	bigint(ll n) { s = to_string(n); };
	bigint(string t) { s = t; };
};
bool operator==(const bigint& a, const bigint& b) { return a.s == b.s; };
bool operator==(const bigint& a, const int& b) { return a.s == to_string(b); };
bool operator!=(const bigint& a, const bigint& b) { return !(a == b); };
bool operator!=(const bigint& a, const int& b) { return a != to_string(b); };
bool operator<(const bigint& a, const bigint& b) {
	if (a.s.length() != b.s.length())return a.s.length() < b.s.length();
	return a.s < b.s;
}
bool operator>(const bigint& a, const bigint& b) {
	if (a.s.length() != b.s.length())return a.s.length() > b.s.length();
	return a.s > b.s;
}
bool operator>=(const bigint& a, const bigint& b) {
	return !(a < b);
}
bool operator<=(const bigint& a, const bigint& b) {
	return !(a > b);
}
bigint operator+(const bigint& a, const bigint& b) {
	int len = max(a.s.length(), b.s.length());
	bigint ret; bool f = false;
	rep(i, len) {
		int c = 0;
		if (f)c = 1, f = false;
		int j = a.s.length() - 1 - i;
		if (j >= 0)c += a.s[j] - '0';
		j = b.s.length() - 1 - i;
		if (j >= 0)c += b.s[j] - '0';
		if (c >= 10)f = true, c -= 10;
		ret.s.push_back('0' + c);
	}
	if (f)ret.s.push_back('1');
	reverse(ret.s.begin(), ret.s.end()); return ret;
}
bigint operator+(const bigint& a, const int b) {
	return a + bigint(b);
}
bigint operator-(const bigint& a, const bigint& b) {
	int len = max(a.s.length(), b.s.length());
	bigint ret; bool f = false;
	rep(i, len) {
		int c = 0;
		if (f)c = -1, f = false;
		int j = a.s.length() - 1 - i;
		if (j >= 0)c += a.s[j] - '0';
		j = b.s.length() - 1 - i;
		if (j >= 0)c -= b.s[j] - '0';
		if (c < 0)f = true, c += 10;
		ret.s.push_back('0' + c);
	}
	while (ret.s.size() > 1 && ret.s.back() == '0')ret.s.pop_back();
	reverse(ret.s.begin(), ret.s.end());
	return ret;
}
bigint operator/(const bigint& a, const bigint& b) {
	bigint ret(0);
	bigint ans;
	int len = a.s.length();
	rep(i, len) {
		ret = ret + (a.s[i] - '0');
		int cnt = 0;
		while (ret >= b)++cnt, ret = ret - b;
		ans.s.push_back('0' + cnt);
		if (ret != 0)ret.s.push_back('0');
	}
	rep(i, ans.s.length()) {
		if (ans.s[i] != '0') {
			ans.s.erase(ans.s.begin(), ans.s.begin() + i);
			break;
		}
		if (i == (int)ans.s.length() - 1) {
			ans = 0;
		}
	}
	return ans;
}
bigint operator%(const bigint& a, const bigint& b) {
	bigint ret(0);
	int len = a.s.length();
	rep(i, len) {
		ret = ret + (a.s[i] - '0');
		while (ret >= b)ret = ret - b;
		if (ret != 0 && i < len - 1)ret.s.push_back('0');
	}

	rep(i, ret.s.size()) {
		if (ret.s[i] != '0' || i == ret.s.size() - 1) {
			ret.s.erase(ret.s.begin(), ret.s.begin() + i);
			break;
		}
	}
	return ret;
}
bigint multi(const bigint& a, const int& t) {
	bigint ret;
	int c = 0;
	per(i, a.s.length()) {
		c += (a.s[i] - '0') * t;
		ret.s.push_back('0' + (c % 10));
		c /= 10;
	}
	while (c > 0) {
		ret.s.push_back('0' + (c % 10));
		c /= 10;
	}
	while (ret != 0 && ret.s.back() == '0')ret.s.pop_back();
	reverse(ret.s.begin(), ret.s.end());
	return ret;
}
/*bigint operator*(const bigint &a, const bigint &b) {
	bigint ret(0);
	int l = b.s.length();
	rep(i, b.s.length()) {
		bigint u = multi(a, (b.s[l - 1 - i] - '0'));
		if (u != 0) {
			rep(j, i)u.s.push_back('0');
		}
		ret = ret + u;
	}
	rep(i, ret.s.size()) {
		if (ret.s[i] != '0' || i == ret.s.size() - 1) {
			ret.s.erase(ret.s.begin(), ret.s.begin() + i);
			break;
		}
	}
	return ret;
}*/
bigint operator*(const bigint& a, const bigint& b) {
	if (a.s.size() + b.s.size() < 18)return stoll(a.s) * stoll(b.s);
	bigint ret;
	ret.s.resize(a.s.size() + b.s.size());
	int c = 0;
	rep(i, ret.s.size()) {
		rep(j, i + 1) {
			if (j < a.s.size() && i - j < b.s.size()) {
				c += (a.s[a.s.size() - 1 - j] - '0') * (b.s[b.s.size() - 1 - (i - j)] - '0');
			}
		}
		ret.s[i] = '0' + (c % 10);
		c /= 10;
	}
	while (ret != 0 && ret.s.back() == '0')ret.s.pop_back();
	reverse(ret.s.begin(), ret.s.end());
	return ret;
}
bigint min(const bigint& a, const bigint& b) {
	if (a < b)return a;
	else return b;
}

bigint gcd(bigint a, bigint b) {
	if (a < b)swap(a, b);
	while (b > 0) {
		bigint r = a % b; a = b; b = r;
	}
	return a;
}
typedef pair<bigint, bigint> bP;
void solve() {
	string s = "1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
	int n; cin >> n;
	bigint b(s); b=b* n;
	s = b.s;
	if (s.size() == 190) {
		s = "0." + s;
	}
	else {
		s.insert(s.end() - 190, '.');
	}
	cout << s << "\n";
}




signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout << fixed << setprecision(10);
	//init_f();
	//init();
	//expr();
	//while(true)
	//int t; cin >> t; rep(i, t)
	solve();
	return 0;
}