import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        System.out.println(ans);
    }

} import java.util.*; util.* java public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        System.out.println(ans);
    }

} Main public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        System.out.println(ans);
    } main {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        System.out.println(ans);
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long N = sc.nextLong(); N sc.nextLong() sc.nextLong sc long n=N; n N long max=(long)Math.pow(10, 15)+1; max (long)Math.pow(10, 15)+1 (long)Math.pow(10, 15) Math.pow Math 10 15 1 String res=""; res "" while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        } N>0 N 0 {
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        } N-- N res = res + (char)('a' + N%26) res res + (char)('a' + N%26) res (char)('a' + N%26) 'a' N%26 N 26 N = N/26 N N/26 N 26 StringBuffer ans = new StringBuffer(res); ans new StringBuffer(res) String hoge2 = ans.reverse().toString(); hoge2 ans.reverse().toString() ans.reverse().toString ans.reverse() ans.reverse ans System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        System.out.println(ans);
    }

} public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        System.out.println(ans);
    }

} Main
import java.util.*;
public class Main {

    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        long N = sc.nextLong();
        long n=N;
        long max=(long)Math.pow(10, 15)+1;
        String res="";
        
        
        while(N>0){
            N--;
            res = res + (char)('a' + N%26);
            N = N/26;
        }
        StringBuffer ans = new StringBuffer(res);
        String hoge2 = ans.reverse().toString();
        System.out.println(ans);
    }

}