import java.util.*;

public class Main {

    public static void main(String[] args) {
        // write your code here
        Scanner sc = new Scanner(System.in);
        long n = sc.nextLong();
        StringBuilder builder = new StringBuilder();
        while (n > 0) {
            long e = (n - 1) % 26;
            char v = (char) (e + 97);
            builder.insert(0, v);
            if (e == 25) {
                n--;
            }
            n /= 26;
        }
        System.out.println(builder);
    }
}
/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