fun main(args: Array<String>) {
    val line = readLine()!!.trim()
    val n: Int = line[0].toInt()
    val a: Int = 'A'.toInt()
    val z: Int = 'Z'.toInt()

    if (a <= n && n <= z) {
        println("A")
    } else {
        println("a")
    }
}