import java.util.Scanner;
import java.util.Arrays;

public class Main{
	public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    }
} import java.util.Scanner; Scanner java.util import java.util.Arrays; Arrays java.util public class Main{
	public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    }
} Main public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    } main {
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    } Scanner scan = new Scanner(System.in); scan new Scanner(System.in) long N = scan.nextLong(); N scan.nextLong() scan.nextLong scan String res = ""; res "" while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      } N != 0 N 0 {
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      } N-- N res += (char)('a' + (N % 26)) res (char)('a' + (N % 26)) 'a' (N % 26) N 26 N /= 26 N 26 StringBuilder builder = new StringBuilder(res); builder new StringBuilder(res) String result = builder.reverse().toString(); result builder.reverse().toString() builder.reverse().toString builder.reverse() builder.reverse builder System.out.println(result) System.out.println System.out System System.out result String args[] args public class Main{
	public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    }
} public class Main{
	public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    }
} Main
import java.util.Scanner;
import java.util.Arrays;

public class Main{
	public static void main(String args[]){
      Scanner scan = new Scanner(System.in);
      long N = scan.nextLong();

      String res = "";
      //Nが0ではない間
      while(N != 0){
          N--;
          res += (char)('a' + (N % 26));
          N /= 26;
      }
      //文字列を反転
      StringBuilder builder = new StringBuilder(res);
      String result = builder.reverse().toString();

      System.out.println(result);
    }
}