#include <iostream>
#include <vector>
#include<map>
#include<string>
#include<algorithm>
#include<sstream>
#include<cmath>
#include<typeinfo>
#include<queue>
using namespace std;
int main() {
	int N, K;
	cin >> N >> K;
	int count;
	if (N % 2 == 1) {
		if (2*(K-1) >= N) {
			count = N;
		}
		else if(K==1){
			count = 2*K;
		}
		else {
			count = 2 * (K - 1);
		}
	}
	else {
		if (2 * K >= N)count = N / 2;
		else count = K;
	}
	cout << count<<endl;
}