import java.util.*;

public class Main {



    public static void main(String[] args) {

        //1_000_000_000_000_001    15


        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();


        StringBuilder sb = new StringBuilder();

        boolean exit = false;
        while(!exit){
            int m = (int)((N-1)%26L);
            char c = (char)('a'+ m);
            sb.insert(0,c);
            N = (N-1)/26L;
            if(N ==0L) exit=true;
        }
        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