// 🐋💭
import Foundation

func main() {
    var n = Int(readLine()!)!
    //_____________________________ここまで入力
    var ans = String()
    var surplus = 0
    while n > 0 {
        n -= 1
        surplus = n % 26
        ans += String(UnicodeScalar(Int("a".unicodeScalars.first!.value) + surplus)!)
        n /= 26
    }
    print(String(ans.reversed()))
}
main()




