#pragma GCC optimize("Ofast") 
#include <bits/stdc++.h>
using namespace std;
using ll = long long int ;
using ld = long double ;
using P = pair<ll,ll>;
using Graph= vector<vector<ll>>;
struct edge{ll to ; ll cost ;} ;
using graph =vector<vector<edge>> ;
#define rep(i,n) for (ll i=0; i < (n); ++i)
#define rep2(i,n,m) for(ll i=n;i<=m;i++)
#define rep3(i,n,m) for(ll i=n;i>=m;i--)
#define pb push_back 
#define eb emplace_back 
#define ppb pop_back 
#define mpa make_pair 
#define fi first  
#define se second  
#define set20 cout<<fixed<<setprecision(20)  ;
const ll INF=1e18 ;   
inline void chmax(ll& a,ll b){a=max(a,b);}  
inline void chmin(ll& a,ll b){a=min(a,b);} 
long double pi=acos(-1) ;  
ll gcd(ll a, ll b) { return b?gcd(b,a%b):a;}  
ll lcm(ll a, ll b) { return a/gcd(a,b)*b;} 
ll dx[4] {1,0,-1,0} ;
ll dy[4] {0,1,0,-1} ;
#define debug cout<<888<<endl ;

// sum(x) x以下の和
// sum(a,b) a以上b以下の和
template<typename T>
struct BIT {
  int n;
  vector<T> d;
  BIT(int n=0):n(n),d(n+1) {}
  void add(int i, T x=1) {  //x=1ならsumは個数のカウント
    for (i++; i <= n; i += i&-i) {
      d[i] += x;
    }
  }
  T sum(int i) {
    T x = 0;
    for (i++; i; i -= i&-i) {
      x += d[i];
    }
    return x;
  }
  T sum(int i,int j) {
    if(i>0) return sum(j)-sum(i-1);
    else return sum(j) ; } 
};



int main(){
  ios::sync_with_stdio(false) ;
  cin.tie(nullptr) ;
  
  ll n,k ; cin>>n>>k ;
  if((n-k)%2==1) cout<<n<<endl ;
  else cout<<n-1<<endl ;

  return 0 ;
}