import java.util.*;
import java.util.Collections;
public class Main {
	public static void main(String[] args){	
      Scanner sc = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    }
} import java.util.*; util.* java import java.util.Collections; Collections java.util public class Main {
	public static void main(String[] args){	
      Scanner sc = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    }
} Main public static void main(String[] args){	
      Scanner sc = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    } main {	
      Scanner sc = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    } Scanner sc = null; sc null sc = new Scanner(System.in) sc new Scanner(System.in) long N = sc.nextLong(); N sc.nextLong() sc.nextLong sc String ans = ""; ans "" while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      } N-- > 0 N-- N 0 {
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      } ans = (char)('a' + (N%26)) + ans ans (char)('a' + (N%26)) + ans (char)('a' + (N%26)) 'a' (N%26) N 26 ans N /= 26 N 26 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 = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    }
} public class Main {
	public static void main(String[] args){	
      Scanner sc = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    }
} Main
import java.util.*;
import java.util.Collections;
public class Main {
	public static void main(String[] args){	
      Scanner sc = null;
      sc = new Scanner(System.in);
      long N = sc.nextLong();
      String ans = "";
     
      while(N-- > 0){
        ans = (char)('a' + (N%26)) + ans;
        N /= 26;
      }
      System.out.println(ans);
    }
}