import java.util.*;
  
public class Main{
    public static void main(final String[] args){
       
        final Scanner sc = new Scanner(System.in);

        String abc = "abcdefghijklmnopqrstuvwxyz";
        Long alf = 26l;
        Long N = sc.nextLong();
        String ans = "";

        for(;N>0;){
            Long Num = N-1;
            int tStr = (int)(Num%alf);
            ans = abc.substring(tStr,tStr+1)+ans;
            N =  Num/alf;
        }
        System.out.println(ans);
    }
}
/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