#include <cstdio>
#include <climits>
#include <cmath>
#include <iostream>
#include <iomanip>
#include <string>
#include <cstdio>
#include <climits>
#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <utility>
#include <queue>
#include <cstring>
#include <set>
#include <map>
#include <complex>

#define rep(i, n) for (int i = 0; i < int(n); i++)
using namespace std;
long long MOD = 1000000007;
long long INF = 1000000000000000; //10^15
typedef long long ll;
typedef unsigned long long ull;


ll powMod(ll x, ll n, ll mod) {
  if (n == 0) return 1;
  ll t = powMod(x, n/2, mod);
  t = t * t % mod;
  if (n & 1) return t * x % mod;
  return t;
}

ll gcd(ll a, ll b) {
  if (a == 0 || b == 0) return a + b;
  if (b > a) return gcd(b, a);
  return gcd(b, a % b);
}




int main(void) {

  ll n, k;
  cin >> n >> k;

  if (n % 2 == 0) n /= 2;

  if (k >= n - 1) cout << n << endl;
  else cout << k + 1 << endl;

  return 0;
}