import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String D = "0.1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192939495969798991";
        int N = sc.nextInt();
        String [] arr = D.split("");
        int [] arr2 = new int [191];
        int u=0;
        for(int i=arr.length-1; i>=2; i--){
            int t = Integer.parseInt(arr[i]);
            t=t*N+u;
            u=t/10;
            t=t%10;
            arr2[i-2]=t;
        }
        System.out.print(u+".");
        for(int i=0; i<arr2.length-1; i++){
            System.out.print(arr2[i]);
        }
        System.out.println();
    }
}