#include 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{ ans=n*(m-1); ll top=1; while (top*2<=m) top*=2; ll bit=1; ll sum=0; while (bit!=top){ if (m&bit){ ans=max(ans,m*(n-2)+(top+bit-1)+(bit+sum)); } else{ sum+=bit; } bit*=2; } } ll ans2=0; vector vec; auto dfs=[&](auto dfs,int v,ll sum,ll val)-> void { if (v==n){ if (val==0){ ans2=max(ans2,sum); if (ans2==-1){ cout<<1<