#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <iomanip>
#include <cmath>
#include <stdio.h>
#include <queue>
#include <deque>
#include <cstdio>
#include <set>
#include <map>
#include <bitset>
#include <stack>
#include <cctype>
using namespace std;
long double pi = 3.1415926535897932384626;
int main() {
	long double h, r;
	cin >> h >> r;
	long double ffc = r * 2 * pi;
	cout << fixed << setprecision(16) << -8.245 + 6.807 * h + 7.073 * ffc << endl;
}