#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main(){
    long double H,FFC;cin>>H>>FFC;
    cout << fixed << setprecision(15) <<  -8.245 + 6.807 * H + 7.073 * (long double)(FFC*2)*acos(-1) << endl;
}
// 8.245 + 6.807 * H + 7.073 * FFC