import java.util.*;
import java.io.*;
public class Main{
	public static void main(String[] args) throws Exception
	{
	  Scanner sc=new Scanner(System.in);
		Long n=sc.nextLong();
		List<Long> li=new ArrayList<Long>();
		Quadrillion(n);
		
		
	}
	public static void Quadrillion(Long n)
	{
		StringBuffer sb=new StringBuffer();
		while(n>0)
		{
			Long x=n%26;
			if(x==0)
			{
				sb.append('z');
				n=n/26-1;
			}
			else
			{
				sb.append((char)((x-1)+'a'));
				n=n/26;
			}
		}
		 System.out.println(sb.reverse());
	}

}

/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