#include <iostream>
#include <vector>
#include <map>


using namespace std;

double solveB(int trials,double t1,double t2)
{
  double prev1,prev2,next;
  prev1 = t1;
  prev2 = t2;
  for(int i = 0 ; i < trials - 2 ; i ++){
    next = prev2 * 2. + 2. - prev1;
    prev1 = prev2;
    prev2 = next;
    if(next < 0) return -1.;
  }
//  cout << next << endl;
  return next;
}

int main(void)
{
  int trials;
  double A;
  cin >> trials;
  cin >> A;

  double NEXTMAX= A;
  double NEXTMIN = 0;

  double MINB, B;
  double NEXT;

  
  for(int i = 0 ; i < 80 ; i ++){
    NEXT = (NEXTMAX + NEXTMIN ) / 2;
    if((B=solveB(trials,A, NEXT)) > 0){
      MINB = B;
      NEXTMAX = NEXT;
    }else{
      NEXTMIN = NEXT;
    }
  }
  printf("%.2f\n", MINB);
}