#include <bits/stdc++.h>
#define rep(i, a, n) for (int i = a; i < n; i++)
#define repr(i, a, n) for (int i = n - 1; i >= a; i--)
using namespace std;
using ll = long long;
using P = pair<int, int>;
template <typename T> void chmin(T &a, T b) { a = min(a, b); }
template <typename T> void chmax(T &a, T b) { a = max(a, b); }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);

  int n, k;
  cin >> n >> k;
  if (n & 1) {
    if (k >= n - 1)
      cout << n << endl;
    else
      cout << k + 1 << endl;
  } else
    cout << min(n / 2, k + 1) << endl;
}