#include "bits/stdc++.h"
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000

int cnt = 0;
int win = 0;

unsigned int randInt() {
	static unsigned int tx = 123456789, ty = 362436069, tz = 521288629, tw = 88675123;
	unsigned int tt = (tx ^ (tx << 11));
	tx = ty; ty = tz; tz = tw;
	return (tw = (tw ^ (tw >> 19)) ^ (tt ^ (tt >> 8)));
}

void game(int K, int roll, int me, int enemy) {
	if (roll == 0) {
		cnt++;
		if (me > enemy) win++;
		return;
	}
	if (K > 0) {
		game(K - 1, roll - 1, me + randInt() % 3 + 4, enemy + randInt() % 6 + 1);
	}
	else {
		game(K - 1, roll - 1, me + randInt() % 6 + 1, enemy + randInt() % 6 + 1);
	}

}

int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
	int N, K; cin >> N >> K;
	rep(i, 5000000) game(K, N, 0, 0);
	//cout << win << " " << cnt << endl;
	cout << fixed;
	cout << setprecision(12) << win / (double)cnt << endl;



    return 0;
}