#include <bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(ri,n) for(int ri = (int)(n-1); ri >= 0; ri--)
#define rep2(i,x,n) for(int i = (int)(x); i < (int)(n); i++)
#define repit(itr,x) for(auto itr = x.begin(); itr != x.end(); itr++)
#define rrepit(ritr,x) for(auto ritr = x.rbegin(); ritr != x.rend(); ritr++)
#define ALL(x) x.begin(), x.end()
using ll = long long;
using namespace std;

int main(){
  int n, k;
  cin >> n >> k;
  bool ne = (n%2 == 0);
  bool ke = (k%2 == 0);
  int ans;
  if(ne == true){
    n /= 2;
    ans = min(n, k+1);
  }else{
    if(ke == true){
      ans = min(n, k+1);
    }else{
      k = (k+1)/2;
      ans = min(n, 2*k);
    }
  }
  cout << ans << endl;
  return 0;
}