#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES

#include "bits/stdc++.h"
#define REP(i,a,b) for(int i=a;i<b;++i)
#define rep(i,n) REP(i,0,n)
#define ll long long
#define ull unsigned ll
typedef long double ld;
#define ALL(a) begin(a),end(a)
#define ifnot(a) if(not (a))
#define dump(x)  cerr << #x << " = " << (x) << endl
using namespace std;

// #define int ll
#ifdef _MSC_VER
const bool test = true;
#else 
const bool test = false;
#endif

int dx[] = { 0,1,0,-1 };
int dy[] = { 1,0,-1,0 };
#define INF (1 << 28)
ull mod = (int)1e9 + 7;
//.....................
#define MAX (int)1e5 + 5

double H, W;

signed main() {

	string d = "0.1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
	string res;
	int N;
	cin >> N;
	int rest = 0;
	reverse(ALL(d));
	int mode = 0;
	rep(i, 540) {
		int v = 0;
		if (mode == 0) {
			if (d[i] == '.') {
				mode = 1;
				//res += ".";
				//continue;
			}
			v = d[i] - '0';
		}
		else {
			if (rest == 0) {
				res += "0.";
				break;
			}
		}
		res += (v + rest) % 10 + '0';
		rest = (v + rest) / 10;
	}




	reverse(ALL(res));
	cout << res << endl;
	return 0;
}