import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        double[] dp = new double[6 * n + 1];
        Arrays.fill(dp, 0);
        Set<Integer> s = new TreeSet<>();
        dp[1] = 1;
        s.add(1);
        while(!s.isEmpty()) {
            int x = s.iterator().next();
            s.remove(x);
            if(x >= n) break;
            s.add(x * 2);
            s.add(x * 3);
            s.add(x * 4);
            s.add(x * 5);
            s.add(x * 6);
            dp[x * 2] += dp[x] * 1.0 / 5.0;
            dp[x * 3] += dp[x] * 1.0 / 5.0;
            dp[x * 4] += dp[x] * 1.0 / 5.0;
            dp[x * 5] += dp[x] * 1.0 / 5.0;
            dp[x * 6] += dp[x] * 1.0 / 5.0;
        }
        System.out.println(dp[n]);
    }
    // there is an extra-log factor because of the usage of HashSet :)
    // clearly standard double precision is insufficient for representing numbers with high precision after the decimal point
    // but you could use BigDecimal
    // but this is still not enough :), best way is to represent the rational numbers in modulo large 'prime number'.
}