import java.util.*;
import java.io.*;
public class Main{
   public static void main(String[] main) throws Exception{
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      PrintWriter out = new PrintWriter(System.out);
      long[] pow = new long[11];
      pow[0] = 26;
      for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1];
     long n = Long.parseLong(st.nextToken());
     int i = 0;
     while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     }
     String ans = "";
     n--;
     while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     }
     out.println(ans);
      out.close();
   }
} import java.util.*; util.* java import java.io.*; io.* java public class Main{
   public static void main(String[] main) throws Exception{
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      PrintWriter out = new PrintWriter(System.out);
      long[] pow = new long[11];
      pow[0] = 26;
      for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1];
     long n = Long.parseLong(st.nextToken());
     int i = 0;
     while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     }
     String ans = "";
     n--;
     while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     }
     out.println(ans);
      out.close();
   }
} Main public static void main(String[] main) throws Exception{
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      PrintWriter out = new PrintWriter(System.out);
      long[] pow = new long[11];
      pow[0] = 26;
      for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1];
     long n = Long.parseLong(st.nextToken());
     int i = 0;
     while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     }
     String ans = "";
     n--;
     while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     }
     out.println(ans);
      out.close();
   } main {
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      PrintWriter out = new PrintWriter(System.out);
      long[] pow = new long[11];
      pow[0] = 26;
      for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1];
     long n = Long.parseLong(st.nextToken());
     int i = 0;
     while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     }
     String ans = "";
     n--;
     while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     }
     out.println(ans);
      out.close();
   } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) StringTokenizer st = new StringTokenizer(br.readLine()); st new StringTokenizer(br.readLine()) PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) long[] pow = new long[11]; pow new long[11] 11 pow[0] = 26 pow[0] pow 0 26 for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1]; int i = 1; int i = 1; i 1 i < 11 i 11 i++ i++ i pow[i] = 26*pow[i-1]; pow[i] = 26*pow[i-1] pow[i] pow i 26*pow[i-1] 26 pow[i-1] pow i-1 i 1 long n = Long.parseLong(st.nextToken()); n Long.parseLong(st.nextToken()) Long.parseLong Long st.nextToken() st.nextToken st int i = 0; i 0 while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     } n > pow[i] n pow[i] pow i {
    	 n -= pow[i];
    	 i++;
     } n -= pow[i] n pow[i] pow i i++ i String ans = ""; ans "" n-- n while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     } i >= 0 i 0 {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     } ans = (char)(97 + n%26) + ans ans (char)(97 + n%26) + ans (char)(97 + n%26) 97 n%26 n 26 ans n /= 26 n 26 i-- i out.println(ans) out.println out ans out.close() out.close out String[] main main public class Main{
   public static void main(String[] main) throws Exception{
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      PrintWriter out = new PrintWriter(System.out);
      long[] pow = new long[11];
      pow[0] = 26;
      for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1];
     long n = Long.parseLong(st.nextToken());
     int i = 0;
     while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     }
     String ans = "";
     n--;
     while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     }
     out.println(ans);
      out.close();
   }
} public class Main{
   public static void main(String[] main) throws Exception{
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      PrintWriter out = new PrintWriter(System.out);
      long[] pow = new long[11];
      pow[0] = 26;
      for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1];
     long n = Long.parseLong(st.nextToken());
     int i = 0;
     while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     }
     String ans = "";
     n--;
     while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     }
     out.println(ans);
      out.close();
   }
} Main
import java.util.*;
import java.io.*;
public class Main{
   public static void main(String[] main) throws Exception{
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st = new StringTokenizer(br.readLine());
      PrintWriter out = new PrintWriter(System.out);
      long[] pow = new long[11];
      pow[0] = 26;
      for(int i = 1; i < 11; i++)
    	  pow[i] = 26*pow[i-1];
     long n = Long.parseLong(st.nextToken());
     int i = 0;
     while(n > pow[i]) {
    	 n -= pow[i];
    	 i++;
     }
     String ans = "";
     n--;
     while(i >= 0) {
    	 ans = (char)(97 + n%26) + ans;
    	 n /= 26;
    	 i--;
     }
     out.println(ans);
      out.close();
   }
}
