#include<bits/stdc++.h>
using namespace std;

int main(){
  using ll=long long;
  ll n,m;
  cin>>n>>m;
  ll ans=0;
  if (n%2==0) ans=n*m;
  else{
    ll top=1;
    while (top*2<=m) top*=2;
    ans+=(top*2-1)-(m-top);
    ans+=(n-2)*m;
    ans+=top-1;
  }
  cout<<ans<<endl;
}