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

#define ll long long
#define rep(i, n) for (int i = 0; i < (n); i++)
#define P pair<int, int>

int main() {
  int n,k;
  cin >> n >> k;
  if (n%2)  cout << min(k+1,n) << endl;
  else cout << min(k+1, n/2) << endl;



}