//package  com.company;


import java.util.Scanner;

public class Main{

    public static void main(String[] args) {
        Scanner sc=new Scanner(System.in);
        StringBuilder ans=new StringBuilder();
        long n=sc.nextLong();
        while(n>0){
            n--;
            ans.append((char) ((n % 26) + 'a'));
            n/=26;
        }
        System.out.println(ans.reverse().toString());

    }
}
/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