fun main(args : Array<String>){
    val alphabet = readLine()
    val answer =Alphabet(alphabet)
    println(answer.get_answer())
}

class Alphabet (input : String?){
    val omikuji = listOf(
        "a",
        "b",
        "c",
        "d",
        "e",
        "f",
        "g",
        "h",
        "i",
        "j",
        "k",
        "l",
        "n",
        "o",
        "p",
        "q",
        "r",
        "s",
        "t",
        "u",
        "v",
        "w",
        "x",
        "y",
        "z"
    )
    val nyuryoku=input
    fun get_answer(): String {
        for (i  in 0..26){
            if (nyuryoku == omikuji[i]){
                return omikuji[i+1]
            }
        }
        return ""
    }
}