import java.lang.StringBuilder
import java.util.StringTokenizer

fun main() {
    val reader = System.`in`.bufferedReader()
    var tokenizer: StringTokenizer = StringTokenizer("")

    fun next(): String {
        while (tokenizer.hasMoreTokens().not()) tokenizer = StringTokenizer(reader.readLine())
        return tokenizer.nextToken()
    }

    fun nextLine() = reader.readLine()

    fun solve() {
        var n = next().toLong()

        var ans = StringBuilder()

        while (n > 0){
            n--
            var rem = n%26
            rem += 97
            ans.append(rem.toChar())
            n/=26
        }

        ans.reverse()
        println(ans.toString())



    }

    solve()


}


