#includebitsstdc++husing namespace std;inline static const nullptr_t _ = ios_basesync_with_stdio0; cintienullptr couttienullptr; return nullptr;;using ll = long long;ll n x a ret;int main

import java.util.Scanner

fun main(args: Array) { val input = Scanner(System.in) val n = input.nextLong() val x = input.nextLong() var ret: Long = 0 for (i in 0 until n) { val a = input.nextLong() ret = maxOf(ret, a or x) } println(ret) }