Imports System

Module Program
    Sub Main(args As String())

        Dim N As Long = Long.Parse(Console.ReadLine())

        Console.WriteLine(Ts(N))

    End Sub

    Public Function Ts(n As Long) As String

        Ts = ""
        If n = 0 Then Exit Function
        n -= 1
        Return (Ts(n \ 26) & Chr(Asc("a") + n Mod 26))

    End Function

End Module
