import java.io.BufferedReader import java.io.InputStream import java.io.InputStreamReader import java.util.* import kotlin.math.abs import kotlin.math.max import kotlin.math.min val MOD = 1_000_000_007L class Solver(stream: InputStream, private val out: java.io.PrintWriter) { fun solve() { val N = ni() val K = ni() val ans = if (N % 2 == 0) { if (K % 2 == 0) { min(N / 2, K + 1) } else { min(N / 2, K + 1) } } else { if (K % 2 == 0) { min(N, K + 1) } else { min(N, K + 1) } } out.println(ans) } private val isDebug = try { // なんか本番でエラーでる System.getenv("MY_DEBUG") != null } catch (t: Throwable) { false } private var tokenizer: StringTokenizer? = null private val reader = BufferedReader(InputStreamReader(stream), 32768) private fun next(): String { while (tokenizer == null || !tokenizer!!.hasMoreTokens()) { tokenizer = StringTokenizer(reader.readLine()) } return tokenizer!!.nextToken() } private fun ni() = next().toInt() private fun nl() = next().toLong() private fun ns() = next() private fun na(n: Int, offset: Int = 0): IntArray { return map(n) { ni() + offset } } private fun nal(n: Int, offset: Int = 0): LongArray { val res = LongArray(n) for (i in 0 until n) { res[i] = nl() + offset } return res } private fun na2(n: Int, offset: Int = 0): Array { val a = Array(2){IntArray(n)} for (i in 0 until n) { for (e in a) { e[i] = ni() + offset } } return a } private inline fun map(n: Int, f: (Int) -> Int): IntArray { val res = IntArray(n) for (i in 0 until n) { res[i] = f(i) } return res } private inline fun debug(msg: () -> String) { if (isDebug) System.err.println(msg()) } private fun debug(a: LongArray) { debug { a.joinToString(" ") } } private fun debug(a: IntArray) { debug { a.joinToString(" ") } } private fun debug(a: BooleanArray) { debug { a.map { if (it) 1 else 0 }.joinToString("") } } private fun debugDim(A: Array) { if (isDebug) { for (a in A) { debug(a) } } } /** * 勝手にimport消されるのを防ぎたい */ private fun hoge() { min(1, 2) max(1, 2) abs(-10) } } fun main() { val out = java.io.PrintWriter(System.out) Solver(System.`in`, out).solve() out.flush() }