/**
 *   @FileName	f.cpp
 *   @Author	kanpurin
 *   @Created	2020.05.15 21:36:11
**/

#include "bits/stdc++.h" 
using namespace std; 
typedef long long ll;

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