#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <bits/stdc++.h>
using namespace std;
using lint = long long int;
using P = pair<int, int>;
using PL = pair<lint, lint>;
#define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i<i##_end_;i++)
#define IFOR(i, begin, end) for(int i=(end)-1,i##_begin_=(begin);i>=i##_begin_;i--)
#define REP(i, n) FOR(i,0,n)
#define IREP(i, n) IFOR(i,0,n)
#define ALL(a)  (a).begin(),(a).end()
constexpr int MOD = 1000000007;
constexpr lint B1 = 1532834020;
constexpr lint M1 = 2147482409;
constexpr lint B2 = 1388622299;
constexpr lint M2 = 2147478017;
constexpr int INF = 2147483647;
void yes(bool expr) {cout << (expr ? "Yes" : "No") << "\n";}
template<class T>void chmax(T &a, const T &b) { if (a<b) a=b; }
template<class T>void chmin(T &a, const T &b) { if (b<a) a=b; }
lint N, M;
lint ans = 0;
void solve(lint x, lint sum, lint cnt) {
  chmax(ans, sum + (N - cnt));
  if(cnt == N) return;
  if(2*x <= M) solve(2*x, sum+2*x, cnt+1);
  if(x > 1 && 2*x-1 <= M) solve(2*x-1, sum+2*x-1, cnt+1);
}
int main()
{
  ios::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  cin >> N >> M;
  solve(1, 1, 1);
  cout << ans << endl;
}