import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        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