import java.util.*
import java.math.*
import java.lang.Math.*

val readString: ()->String = {readLine()!!}
val readInt: ()->Int = {readLine()!!.toInt()}
val readLong: ()->Long = {readLine()!!.toLong()}
val readIntArray: ()->IntArray = {readLine()!!.split(' ').map{it.toInt()}.toIntArray()}
val readLongArray: ()->LongArray = {readLine()!!.split(' ').map{it.toLong()}.toLongArray()}
val errPrintln: (String)->Unit = {msg -> System.err.println(msg)}
val MOD = 1_000_000_007L
val INF = Int.MAX_VALUE/2
val LINF = Long.MAX_VALUE/2
data class IntPair(val first: Int, val second: Int)
data class To(val idx: Int, val cost: Long)


fun solve() {
}


fun main(args: Array<String>) {
    val C = readString().toCharArray()[0]

    val ans = if ('A' <= C && C <= 'Z') 'A' else 'a'
    println(ans)
}
