#include<bits/stdc++.h>
using namespace std;
using ll = long long int;
using ld = long double;
#define pow(n,m) powl(n,m);
#define sqrt(n) sqrtl(n);
const ll MAX = 5000000000000000000;
const ll MOD = 1000000007;
//998244353;
void randinit(){srand((unsigned)time(NULL));}
int main(){
    ld H,R;
    cin >> H >> R;
    cout << -8.245 + 6.807 * H + 7.73 * R * 2 * 3.141592653589793238 << endl;
}