fun main() {
    var n = nextLong()
    println(buildString {
        while (n > 0) {
            append('a' + ((n - 1) % 26).toInt())
            if (n % 26 == 0L) {
                n -= 1
            }
            n /= 26
        }
    }.reversed())
}

val sc = java.util.Scanner(System.`in`)
fun next(): String = sc.next()
fun nextInt() = sc.nextInt()
fun next2Int() = Pair(nextInt(), nextInt())
fun next3Int() = Triple(nextInt(), nextInt(), nextInt())
fun nextIntArray(size: Int) = IntArray(size) { nextInt() }
fun nextLong() = sc.nextLong()
fun nextLine(): String = sc.nextLine()