fun main() = Thread(null, ::abc171c, "(^o^)", 128 * 1024 * 1024).apply { start() }.join()

@OptIn(ExperimentalStdlibApi::class)
fun abc171c() {
    val n = readLine()!!.toLong()

    val answer = StringBuilder()

    var currN = n

    while (currN > 0) {
        currN--
        val rem = currN % 26
        answer.append(rem.toChar() + 'a'.toInt())
        currN /= 26
    }

    println(answer.reversed())
}
