fun main(args: Array<String>) {

    val n = readLine()!!.toLong()


    var (i,j) = test(n)

    var ans = ""
    while (true){
       ans =  ('a'+j.toInt()) + ans
        if(i == 0L){
            break
        }
        val p = test(i)
        i = p.first
        j = p.second
    }

    println(ans)
}

fun test(n: Long) = (n-1) / 26 to (n-1 ) % 26

