#define _GLIBCXX_DEBUG
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
#define ALL(v) v.begin(), v.end()
typedef long long ll;

template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }

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


int main(){
  ll n,k;
  cin>>n>>k;
  
  if(n%2==0){
    if(k+1<=n/2) cout<<k+1<<endl;
    else cout<<n/2<<endl;
  }
  else{
    if(k+1<=n) cout<<k+1<<endl;
    else cout<<n<<endl;
  }
  
  
  return 0;
}