#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
using ll=long long;
using Graph=vector<vector<int>>;
#define MAX 1000000
#define MOD 1000000009
//#define MOD 998244353
#define INF 1000000000
//#define INF 1000000000000000000

int main(){
  double H,R;
  cin>>H>>R;
  double ans=-8.245+6.807*H+7.073*R*2.0*M_PI;
  printf("%.9lf\n",ans);
}