#include <bits/stdc++.h>
using namespace std;
// #include<atcoder/all>
// using mint = atcoder::modint998244353;
using ld = long double;
#define fi first
#define se second
#define all(x) x.begin(),x.end()
#define rep(i,n) for(int i=0;i<(int)(n);++i)
template<typename T>bool chmin(T&a,T b){return b<a?(a=b,1):0;}
template<typename T>bool chmax(T&a,T b){return b>a?(a=b,1):0;}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    long N,M;
    cin>>N>>M;
    if(N%2==0){
        cout<<N*M<<"\n";
        return 0;
    }
    if(N==1){
        cout<<0<<"\n";
        return 0;
    }
    long ma=0;
    for(long i=1;i-1<=M;i<<=1){
        if(((i-1)^M)<=M){
            chmax(ma, (i-1)+((i-1)^M));
        }
    }
    cout<<(N-2)*M+ma<<"\n";

}