import java.io.PrintWriter
import java.util.*
import kotlin.math.*

fun PrintWriter.solve() {
    val n = nextInt()
    val k = nextInt()
    val a = Array(n) { nextInt() }
    val b = Array(n) { nextInt() }
    val lst = (0 until n).sortedByDescending { a[it] - b[it] }.take(k)
    val choice = BooleanArray(n) { false }
    lst.forEach { choice[it] = true }
    println(choice.map { if (it) 'A' else 'B' }.joinToString(""))
}

fun main() {
    val writer = PrintWriter(System.out, false)
    writer.solve()
    writer.flush()
}

// region Scanner
private var st = StringTokenizer("")
private val br = System.`in`.bufferedReader()

fun next(): String {
    while (!st.hasMoreTokens()) st = StringTokenizer(br.readLine())
    return st.nextToken()
}

fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextLine() = br.readLine()
fun nextDouble() = next().toDouble()
// endregion