#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline T POW(T B, T P) {
  if (P == 0) return 1;
  if (P & 1)
    return B * POW(B, P - 1);
  else
    return SQR(POW(B, P / 2));
}
template <typename T>
inline T ModInv(T b, T m) {
  return BigMod(b, m - 2, m);
}
template <typename T>
inline T ABS(T a) {
  if (a < 0)
    return -a;
  else
    return a;
}
template <typename T>
inline T gcd(T a, T b) {
  if (a < 0) return gcd(-a, b);
  if (b < 0) return gcd(a, -b);
  return (b == 0) ? a : gcd(b, a % b);
}
template <typename T>
inline T lcm(T a, T b) {
  if (a < 0) return lcm(-a, b);
  if (b < 0) return lcm(a, -b);
  return a * (b / gcd(a, b));
}
template <class T>
inline T BMOD(T p, T e, T m) {
  T ret = 1;
  while (e) {
    if (e & 1) ret = (ret * p) % m;
    p = (p * p) % m;
    e >>= 1;
  }
  return (T)ret;
}
int main() {
  long long int n, x;
  scanf("%lld%lld", &n, &x);
  double ans = 3.0 * x + (1.0) * (x / 2.0) + 3.0 * (x / 3.0);
  printf("%lf", ans);
  return 0;
}
