#include<iostream>
#include<iomanip>
#include<cmath>
#include<string>
#include<vector>
#include<list>
#include<algorithm>
#include<map>
#include<set>
#include<queue>
#include<stack>
using namespace std;
typedef long long ll;
#define fi first
#define se second
#define mp make_pair
#define rep(i, n) for(int i=0;i<n;++i)
#define rrep(i, n) for(int i=n;i>=0;--i)
const int inf=1e9+7;
const ll mod=1e9+7;
const ll big=1e18;
const double PI=3.14159265359;

int main() {
    ll N, K;
    cin>>N>>K;
    if(N%2==0){
        cout<<min(K+1, N/2)<<endl;
    }
    else{
        cout<<min(K+1, N)<<endl;
    }
}