import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.io.OutputStream;
import java.util.StringTokenizer;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashMap;
import java.util.Map;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.math.BigDecimal;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        solver.solve(1, in, out);
        out.close();
    }

    static class Task {
        public void solve(int testNumber, InputReader in, PrintWriter out) {
            String D = "001234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
            int N = in.nextInt();
            int[] a = new int[192];
            int first = N%10;
            int second = N/10;
            int c=0;
            for(int i=191; i>=0; i--){
                a[i] = (D.charAt(i)-'0')*first+c;
                c=a[i]/10;
                a[i]=a[i]%10;
            }
            c=0;
            for(int i=190; i>=0; i--){
                a[i] = (D.charAt(i+1)-'0')*second+a[i]+c;
                c=a[i]/10;
                a[i]=a[i]%10;
            }

            if(N==100){
                for(int i=191; i>=2; i--){
                    a[i-2] = D.charAt(i)-'0';
                }
            }

            if(a[0]!=0) out.print(a[0]);
            out.print(a[1]+".");
            for(int i=2; i<192; i++){
                out.print(a[i]);
            }
        }
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }

    }
}