import java.util.*

fun main(args: Array<String>) {
    val scan = Scanner(System.`in`)
    var kotlin=scan.nextLine().toLong()
    var ans = ""

    while(kotlin>0)
    {
        var x : Long = kotlin%26
        ans+=getchar(x)
        if(x==0.toLong())
            kotlin=(kotlin/26)-1
        else
        {
            if (kotlin == 26.toLong())
                kotlin = 0
            else
                kotlin /= 26
        }
    }
    ans=ans.reversed()
    println(ans)

}

fun getchar(n : Long) : Char
{
    if(n==0.toLong())
        return 'z'
    var n :Long = (n)+96
    return n.toChar()
}
