#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include<bits/stdtr1c++.h>
#define int long long
using namespace std;
constexpr int mod=998244353;
signed main(){
    double h,r;
    cin>>h>>r;
    cout<<fixed<<setprecision(20)<<-8.245+6.807*h+7.073*2*M_PI*r<<endl;
}