import java.util.*;
import java.io.PrintWriter;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong()-1;
		ArrayList<Character> list=new ArrayList<>();
		while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		}
		for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		}
	}
} import java.util.*; util.* java import java.io.PrintWriter; PrintWriter java.io public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong()-1;
		ArrayList<Character> list=new ArrayList<>();
		while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		}
		for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		}
	}
} Main public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong()-1;
		ArrayList<Character> list=new ArrayList<>();
		while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		}
		for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		}
	} main {
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong()-1;
		ArrayList<Character> list=new ArrayList<>();
		while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		}
		for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		}
	} Scanner sc=new Scanner(System.in); sc new Scanner(System.in) long n=sc.nextLong()-1; n sc.nextLong()-1 sc.nextLong() sc.nextLong sc 1 ArrayList<Character> list=new ArrayList<>(); list new ArrayList<>() while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		} n>=0 n 0 {
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		} list.add((char)('a'+n%26)) list.add list (char)('a'+n%26) 'a' n%26 n 26 n/=26 n 26 n-- n for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		} int i=list.size()-1; int i=list.size()-1; i list.size()-1 list.size() list.size list 1 i>=0 i 0 i-- i-- i {
			System.out.print(list.get(i));
		} {
			System.out.print(list.get(i));
		} System.out.print(list.get(i)) System.out.print System.out System System.out list.get(i) list.get list i String[] args args public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong()-1;
		ArrayList<Character> list=new ArrayList<>();
		while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		}
		for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		}
	}
} public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong()-1;
		ArrayList<Character> list=new ArrayList<>();
		while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		}
		for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		}
	}
} Main
import java.util.*;
import java.io.PrintWriter;

public class Main{
	public static void main(String[] args){
		Scanner sc=new Scanner(System.in);
		long n=sc.nextLong()-1;
		ArrayList<Character> list=new ArrayList<>();
		while(n>=0){
			list.add((char)('a'+n%26));
			n/=26;
			n--;
		}
		for(int i=list.size()-1; i>=0; i--){
			System.out.print(list.get(i));
		}
	}
}
