import java.util.*;
import java.io.*;
class Main{
	public static void main(String[] args) {
	Scanner sc=new Scanner(System.in);
	 long c=sc.nextLong();
	 String[] letter = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

	 
	 long i=0;
	 int j=0;
	 String str="";
	 while(c>26)
	 {
	 	
	 	i=c/26;
	 	if(c%26==0)
	 	{
	 		i=i-1;
	 	}
	 	j=(int)(c%26);
	 	if(j==0){
	 	str=letter[25]+str;

	 	}
	 	else{
	 	str=letter[j-1]+str;

	 	}
	 	c=i;

	 }
	 int x = (int)c;
	 str=letter[x-1]+str;
	 
	 
	System.out.println(str);
	
				
		
	}
}
/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