#include <iostream>
#include <iomanip>
#include <algorithm>

using namespace std;

double pNormalSum[11][61] = { 0.0 }; // [# of dices][sum]
double pFakeSum[11][61] = { 0.0 }; // [# of dices][sum]
double pTaroSum[61];
double pJiroSum[61];
const double pNormalDice[7] = { 0, 1. / 6., 1. / 6., 1. / 6., 1. / 6., 1. / 6., 1. / 6. };
const double pFakeDice[7] = { 0, 0, 0, 0, 1. / 3., 1. / 3., 1. / 3. };

void solveSum(double pSum[11][61], const double pDice[7], int n) {
	pSum[0][0] = 1.0;
	for (int x = 1; x <= 6; ++x) {
		pSum[1][x] = pDice[x];
	}
	for (int i = 1; i <= n; ++i) {
		for (int x = 1; x <= 6 * n; ++x) {
			pSum[i][x] = 0.0;
			for (int k = 6; k >= 1; --k) {
				pSum[i][x] += pSum[i - 1][x - k] * pDice[k];
			}
		}
	}
}

int main() {
	int n, k;
	cin >> n >> k;
	solveSum(pNormalSum, pNormalDice, n);
	solveSum(pFakeSum, pFakeDice, k);
	for (int sum = 1; sum <= 6 * n; ++sum) {
		pTaroSum[sum] = 0.0;
		for (int fakeSum = 0; fakeSum <= min(6 * k, sum); ++fakeSum) {
			int normalSum = sum - fakeSum;
			pTaroSum[sum] += pNormalSum[n - k][normalSum] * pFakeSum[k][fakeSum];
		}
		pJiroSum[sum] = pNormalSum[n][sum];
	}
	double pTaroWin = 0.0;
	for (int taroSum = 1; taroSum <= 6 * n; ++taroSum) {
		for (int jiroSum = 1; jiroSum < taroSum; ++jiroSum) {
			pTaroWin += pTaroSum[taroSum] * pJiroSum[jiroSum];
		}
	}
	cout << fixed << setprecision(6) << pTaroWin << endl;
	return 0;
}