#include <bits/stdc++.h>
using namespace std;
#define FOR(i, n) for(int i = 0; i < (n); i++)
#define MEM(a, x) memset(a, x, sizeof(a))
#define ALL(a) a.begin(), a.end()
#define UNIQUE(a) a.erase(unique(ALL(a)), a.end())
typedef long long ll;
typedef pair<int, int> P;

int n;

int main(int argc, char const *argv[]) {
	ios_base::sync_with_stdio(false);
	cin >> n;
	double one = pow(1/6.0, n);
	double two = pow(2/6.0, n) - 2*one;
	double three = pow(3/6.0, n) - 3*one - 3*two;
	double four = pow(4/6.0, n) - 4*one - 6*two - 4*three;
	double five = pow(5/6.0, n) - 5*one - 10*two - 10*three - 5*four;
	double six = 1.0 - 6*one - 15*two - 20*three - 15*four - 6*five;

	printf("%.10lf\n", six);
	return 0;
}