import java.util.*;
import java.io.*;
public class Main
{
    public static void main(String ars[])throws Exception
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        PrintWriter pw=new PrintWriter(System.out);
        //String str[]=br.readLine().split(" ");
        long n=Long.parseLong(br.readLine());
        //int k=Integer.parseInt(str[1]);
        StringBuffer sb=new StringBuffer();
        while(n>0)
        {
            int mod=(int)((n-1)%26);
            sb.append((char)(mod+97));
            n=(n-1)/26;
        }
        sb.reverse();
        pw.println(sb.toString());
        pw.flush();
        pw.close();
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz