#pragma GCC optimize("O3", "unroll-loops")

#include <bits/stdc++.h>

using namespace std;

#define ll long long

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