#include <iostream>
#include <bits/stdc++.h>
using namespace std;
#define ll long long 
int main() {
    ll n,k;
    cin>>n>>k;
    if(n%2==0){
        ll t=min(n/2,k+1);
        cout<<t<<endl;
    }
    else{
        ll t=min(n,k+1);
        cout<<t<<endl;
    }
    return 0;
}