import java.util.*;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        long num = sc.nextLong();
        System.out.print(read(num));
    }

    private static String read(long num) {
        if(num<=26) {
            char c = (char)(num+96);
            return String.valueOf(c);
        } else {
            long b = num%26;
            char c = (char)(b+96);
            num = num/26;

            if (b==0) {
                num -= 1;
                c = 'z';
            }
            return read(num) + c;
        }
    }

}
/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