#include <bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VL;
typedef vector<VL> VVL;
typedef pair<int, int> PII;

#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
#define MOD 1000000007
#define INF (1LL<<25)     //33554432
#define PI 3.14159265359
#define EPS 1e-12
//#define int ll

signed main(void)
{
  int p, c, a[] = {2, 3, 5, 7, 11, 13}, b[] = {4, 6, 8, 9, 10, 12};
  double dp[20][6] = {0};
  cin >> p >> c;
  REP(i, 6) dp[0][i] = 1;

  FOR(i, 1, p+1) {
    REP(j, 6) {
      REP(k, 6) {
        dp[i][j] += dp[i-1][k] * a[j] / 6;
      }
    }
  }

  FOR(i, p+1, p+c+1) {
    REP(j, 6) {
      REP(k, 6) {
        dp[i][j] += dp[i-1][k] * b[j] / 6;
      }
    }
  }

  /*REP(i, c+p+1) {
    REP(j, 6) {
      cout << dp[i][j] << " ";
    }
    cout << endl;
  }*/

  double ret = 0;
  REP(i, 6) {
    //cout << dp[p+c][i] << " ";
    ret += dp[p+c][i]/6;
  }
  //cout << endl;
  cout << fixed << setprecision(15) << ret << endl;

  return 0;
}