import Foundation

func readInt() -> Int {
    return Int(readLine()!)!
}

func readString() -> String {
    return readLine()!
}

func readLines(times: Int) -> [String] {
    var array: [String] = []
    for _ in 0..<times {
        array.append(readLine()!)
    }
    return array
}

func readSeparatedStrings() -> [String] {
    return readLine()!.split(separator: " ").map({String($0)})
}

func readSeparatedInts() -> [Int] {
    return readLine()!.split(separator: " ").map({Int($0)!})
}

let x = readString()
let pattern = "[A-Z]"
let regex = try! NSRegularExpression(pattern: pattern, options: [])

if regex.firstMatch(in: x, options: [], range: NSRange(location: 0, length: x.count)) != nil {
    print("A")
} else {
    print("a")
}

