import java.util.*;

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

        long n = sc.nextLong();

        System.out.println(base26(n));

    }

    static String base26(long n) {
        StringBuilder buf = new StringBuilder();
        while (n != 0) {
            buf.append((char) ((n - 1) % 26 + 'a'));
            n = (n - 1) / 26;
        }
        return buf.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