import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner koko = new Scanner(System.in);
        int k = koko.nextInt();
        double[] ex = new double[k];
        if(k>6){
            ex[k-1]=1;
            ex[k-2]=(double)7/6;
            ex[k-3]=(double)49/36;
            ex[k-4]=(double)343/216;
            ex[k-5]=(double)2401/1296;
            ex[k-6]=(double)50041/23328;
            for(int i=k-7; i>=0; i--){
                ex[i]=1+(double)ex[i+1]/6+(double)ex[i+2]/6+(double)ex[i+3]/6+(double)ex[i+4]/6+(double)ex[i+5]/6+(double)ex[i+6]/6;
            }
            System.out.println(ex[0]);
        }else if(k==1){
            System.out.println(1);
        }else if(k==2){
            System.out.println((double)7/6);
        }else if(k==3){
            double a= (double)49/36;
            System.out.println(a);
        }else if(k==4){
            System.out.println((double)343/216);
        }else if(k==5){
            System.out.println((double)2401/1296);
        }else if(k==6){
            System.out.println((double)50041/23328);
        }
        
    }
}