import java.util.*;
public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    }
    String ans = sb.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();
    StringBuilder sb = new StringBuilder();
    while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    }
    String ans = sb.toString();
    System.out.println(ans);
  }
} Main public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    }
    String ans = sb.toString();
    System.out.println(ans);
  } main {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    }
    String ans = sb.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 StringBuilder sb = new StringBuilder(); sb new StringBuilder() while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    } true {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    } n-- n sb.insert(0, (char) ('a' + n % 26)) sb.insert sb 0 (char) ('a' + n % 26) 'a' n % 26 n 26 n /= 26 n 26 if (n == 0) {
        break;
      } n == 0 n 0 {
        break;
      } break; String ans = sb.toString(); ans sb.toString() sb.toString sb 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();
    StringBuilder sb = new StringBuilder();
    while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    }
    String ans = sb.toString();
    System.out.println(ans);
  }
} public class Main {
  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long n = sc.nextLong();
    StringBuilder sb = new StringBuilder();
    while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    }
    String ans = sb.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();
    StringBuilder sb = new StringBuilder();
    while (true) {
      n--;
      sb.insert(0, (char) ('a' + n % 26));
      n /= 26;
      if (n == 0) {
        break;
      }
    }
    String ans = sb.toString();
    System.out.println(ans);
  }
}
