#include <bits/stdc++.h>
using namespace std;
const int INF=999999999;
char a[10][10];
int main() {
    int N,K;
    cin>>N>>K;
    if(N%2==0){cout<<min(N/2,K+1)<<endl;}
    else{cout<<min(N,K+1)<<endl;}

 return 0;}