#include <bits/stdc++.h>
using namespace std;
double T[100], Z[100], t[100];
int N, K;

void solve(double *p, int Kf) {
    for(int i = 0; i < 100; i++) {
        t[i] = 0;
    }
    for(int i = 0; i < N; i++) {
        for(int j = 0; j < 100; j++) {
            if (i < Kf) {
                for (int k = 4; k <= 6; k++) {
                    t[(j + k) % 100] += p[j] / 3;
                }
            } else {
                for(int k = 1; k <= 6; k++) {
                    t[(j + k) % 100] += p[j] / 6;
                }
            }
        }
        for(int j = 0; j < 100; j++) {
            p[j] = t[j];
            t[j] =  0;
        }
    }
}

int main() {
    #ifdef DEBUG
    std::ifstream in("/home/share/inputf.in");
    std::cin.rdbuf(in.rdbuf());
    #endif
    for(int i = 0; i < 100; i++) {
        T[i] = Z[i] = 0;
    }
    T[0] = Z[0] = 1;
    cin >> N >> K;
    solve(T, K);
    solve(Z, 0);
    double ans = 0;
    double x = 0;
    for(int i = 99; i >= 0; i--) {
        x += T[i + 1];
        ans += x * Z[i];
    }
    cout << std::fixed << std::setprecision(10) << ans << endl;
    return 0;
}