import java.util.*;

public class Main {

    public static void main(String[] args) {
	// write your code here
        Scanner sc = new Scanner(System.in);
        long inu = sc.nextLong();

        StringBuilder sb = new StringBuilder();
        while (inu > 0) {
            inu -= 1;
            long a = inu % 26;
            inu /= 26;
            char c = (char)(a + 'a');
            sb.insert(0, c);
        }

        System.out.println(sb.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