import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        long n = s.nextLong();
        String a = "";
        long counter = 0;
        while(n>0){
            counter= (n-1)%26;
            char a1 = (char)('a'+counter);
            a=a1+a;
            n = (n-1)/26;
        }
        System.out.println(a);
    }
}

/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