#define _USE_MATH_DEFINES
#include  <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include<math.h>
#include<iomanip>
#include<stdio.h>
#include <stdlib.h>
#include<stdio.h>
#include <queue>
#include<map>
#include <fstream>
#include <sstream>
#include<set>
#include<stack>
#include<time.h>
#include <sys/types.h>
#include <tuple>
#include <numeric>
#include <iterator>
#include <atcoder/all>
#include <bits/stdc++.h>

#define rep(i,n) for (int i = 0; i < (n); ++i)
using namespace atcoder;
using namespace std;
typedef long long int ll;
typedef modint998244353 mint;




ll gcd(ll a, ll b) {
    if (a < b)swap(a, b);
    if (b == 0)return a;

    return gcd(b, a % b);
}
int lcm(int a, int b) {
    return a * b / gcd(a, b);
}

/*
解説動画参考
解説ブログ参考

*/



int main()
{

    int Q;
    Q = 1;
    //cin >> Q;   
    
    
    while (Q--) {
        int n, k;
        cin >> n >> k;
        double a = 0;
        for (int i = 0; i < 1e6; i++) {
            int t = 0;
            int j = 0;
            for (; j < k; j++)t += rand() % 3 + 4;
            for (; j < n; j++)t += rand() % 6 + 1;

            for (j = 0; j < n; j++)t -= (rand() % 6 + 1);
            if (t > 0)a++;
        }
        cout << a / 1e6;
    }

    return 0;
}