#include <bits/stdc++.h>
using namespace std;
const long long LLMAX = 2e18;
const int MOD = 1e9 + 7;
const int MAXN = 1e6 + 10;
template <class T>
inline void read(T &DataIn) {
  DataIn = 0;
  T Flag = 0;
  char c = getchar();
  while (!isdigit(c)) {
    Flag |= c == '-';
    c = getchar();
  }
  while (isdigit(c)) {
    DataIn = DataIn * 10 + c - '0';
    c = getchar();
  }
  DataIn = Flag ? -DataIn : DataIn;
}
template <class T>
inline void write(T DataOut, char EndChar = '\n') {
  T lenth = 0, number[30];
  if (DataOut == 0) {
    putchar(48);
    putchar(EndChar);
    return;
  }
  while (DataOut > 0) {
    number[++lenth] = DataOut % 10;
    DataOut /= 10;
  }
  for (int i = lenth; i >= 1; i--) putchar(number[i] + 48);
  putchar(EndChar);
}
priority_queue<int, vector<int>, less<int> > qd;
priority_queue<int, vector<int>, greater<int> > qu;
int main(void) {
  FILE *fin = NULL, *fout = NULL;
  ios::sync_with_stdio(false);
  cin.tie(0);
  double n, r, R;
  cin >> n >> r;
  double alpha = 3.1415926535898 / n;
  cout << setiosflags(ios::fixed) << setprecision(8)
       << sin(alpha) / (1.0 - sin(alpha)) * r << endl;
  return 0;
}
