Imports System

Module Program
    Sub Main(args As String())

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

        Console.WriteLine(ts(N))

    End Sub

    Public Function ts(n As Long) As String

        Dim ret As String = ""
        If n > 26 Then
            If n \ 26 > 0 Then
                ret = ts(n - (CLng(n \ 26) * 26))
                n -= CLng(n \ 26) * 26
            End If
        End If
        If n <= 26 Then
            ret &= Chr(97 + (n - 1))
        End If
        ts = ret

    End Function

End Module
