import java.lang.StringBuilder

fun main() {
    var n = nextLong()
    val res = StringBuilder()
    while (n > 0) {
        var m = n % 26
        n /= 26
        if (m == 0L) {
            m = 26
            n--
        }
        res.insert(0, m.plus(96).toChar())
    }
    println(res.toString())
}

// # Utils
// ## Input
fun next() = readLine()!!
fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextDouble() = next().toDouble()
fun nextList() = next().split(" ")
fun nextIntList() = next().split(" ").map(String::toInt)
fun nextLongList() = next().split(" ").map(String::toLong)
fun nextDoubleList() = next().split(" ").map(String::toDouble)

// ## Array
inline fun <reified T> sizedArray(size: Int, default: T) = Array(size) { default }
