#include<bits/stdc++.h>
using namespace std;
using u64 = uint_least64_t;
using s64 = int_least64_t;
using ll = uint_least64_t;

int main(){
	double h,r;
	cin >> h >> r;
	double s = -8.245 + 6.807*h + 7.073*2*r*M_PI;
	cout << s << endl;
	return 0;
}