import java.io.*;
import java.math.*;
import java.util.*;


public class Main_yukicoder428 {

	private static Scanner sc;
	private static Printer pr;

	private static void solve() {
		BigDecimal d = new BigDecimal("0.1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991");

		int n = sc.nextInt();

		BigDecimal ret = d.multiply(BigDecimal.valueOf(n));

		pr.println(ret);
	}

	// ---------------------------------------------------
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		pr = new Printer(System.out);

		solve();

		pr.close();
		sc.close();
	}

	private static class Printer extends PrintWriter {
		Printer(PrintStream out) {
			super(out);
		}
	}
}