import java.util.*;import java.io.*;import java.math.*;
public class Main{
  //↓見なくていいよ！ここから------------------------------------------
  static class InputIterator{
    ArrayList<String> inputLine = new ArrayList<String>(1024);
    int index = 0; int max;
    InputIterator(){
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    }
    boolean hasNext(){return (index < max);}
    String next(){
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    }
  }
  
  static InputIterator ii = new InputIterator();//リアクティブでは使えないので諦めてScanner使うこと
  static PrintWriter out = new PrintWriter(System.out);
  static void flush(){out.flush();}
  static void myout(Object t){out.println(t);}
  static void myerr(Object t){System.err.println(t);}
  static String next(){return ii.next();}
  static int nextInt(){return Integer.parseInt(next());}
  static long nextLong(){return Long.parseLong(next());}
  static ArrayList<String> nextStrArray(){return myHanSpSplit(next());}
  static ArrayList<String> myHanSpSplit(String str){return new ArrayList<String>(Arrays.asList(str.split(" ")));}
  static ArrayList<String> nextCharArray(){return mySingleSplit(next());}
  static ArrayList<String> mySingleSplit(String str){return new ArrayList<String>(Arrays.asList(str.split("")));}
  static ArrayList<Integer> nextIntArray(){
    ArrayList<Integer> ret = new ArrayList<Integer>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    }
    return ret;
  }
  static ArrayList<Long> nextLongArray(){
    ArrayList<Long> ret = new ArrayList<Long>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    }
    return ret;
  }
  static String kaigyoToStr(String[] list){return String.join("\n",list);}
  static String kaigyoToStr(ArrayList<String> list){return String.join("\n",list);}
  static String hanSpToStr(String[] list){return String.join(" ",list);}
  static String hanSpToStr(ArrayList<String> list){return String.join(" ",list);}
  public static void main(String[] args){
    solve();
    flush();
  }
  //↑見なくていいよ！ここまで------------------------------------------
  static void solve(){//ここがメイン関数代わり
    long N = nextLong();
    String output = "";
    HashMap<Integer, String> map = new HashMap<Integer, String>();
    ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz");
    for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    }
    map.put(0,"z");
    int count = 1;
    while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    }
    myerr(N);
    myerr(count);
    while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    }
    myout(output);
  }
  //Method addition frame start

  //Method addition frame end
} import java.util.*; util.* java import java.io.*; io.* java import java.math.*; math.* java public class Main{
  //↓見なくていいよ！ここから------------------------------------------
  static class InputIterator{
    ArrayList<String> inputLine = new ArrayList<String>(1024);
    int index = 0; int max;
    InputIterator(){
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    }
    boolean hasNext(){return (index < max);}
    String next(){
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    }
  }
  
  static InputIterator ii = new InputIterator();//リアクティブでは使えないので諦めてScanner使うこと
  static PrintWriter out = new PrintWriter(System.out);
  static void flush(){out.flush();}
  static void myout(Object t){out.println(t);}
  static void myerr(Object t){System.err.println(t);}
  static String next(){return ii.next();}
  static int nextInt(){return Integer.parseInt(next());}
  static long nextLong(){return Long.parseLong(next());}
  static ArrayList<String> nextStrArray(){return myHanSpSplit(next());}
  static ArrayList<String> myHanSpSplit(String str){return new ArrayList<String>(Arrays.asList(str.split(" ")));}
  static ArrayList<String> nextCharArray(){return mySingleSplit(next());}
  static ArrayList<String> mySingleSplit(String str){return new ArrayList<String>(Arrays.asList(str.split("")));}
  static ArrayList<Integer> nextIntArray(){
    ArrayList<Integer> ret = new ArrayList<Integer>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    }
    return ret;
  }
  static ArrayList<Long> nextLongArray(){
    ArrayList<Long> ret = new ArrayList<Long>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    }
    return ret;
  }
  static String kaigyoToStr(String[] list){return String.join("\n",list);}
  static String kaigyoToStr(ArrayList<String> list){return String.join("\n",list);}
  static String hanSpToStr(String[] list){return String.join(" ",list);}
  static String hanSpToStr(ArrayList<String> list){return String.join(" ",list);}
  public static void main(String[] args){
    solve();
    flush();
  }
  //↑見なくていいよ！ここまで------------------------------------------
  static void solve(){//ここがメイン関数代わり
    long N = nextLong();
    String output = "";
    HashMap<Integer, String> map = new HashMap<Integer, String>();
    ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz");
    for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    }
    map.put(0,"z");
    int count = 1;
    while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    }
    myerr(N);
    myerr(count);
    while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    }
    myout(output);
  }
  //Method addition frame start

  //Method addition frame end
} Main static InputIterator ii = new InputIterator();//リアクティブでは使えないので諦めてScanner使うこと ii new InputIterator() static PrintWriter out = new PrintWriter(System.out); out new PrintWriter(System.out) static void flush(){out.flush();} flush {out.flush();} out.flush() out.flush out static void myout(Object t){out.println(t);} myout {out.println(t);} out.println(t) out.println out t Object t t static void myerr(Object t){System.err.println(t);} myerr {System.err.println(t);} System.err.println(t) System.err.println System.err System System.err t Object t t static String next(){return ii.next();} next {return ii.next();} return ii.next(); ii.next() ii.next ii static int nextInt(){return Integer.parseInt(next());} nextInt {return Integer.parseInt(next());} return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next static long nextLong(){return Long.parseLong(next());} nextLong {return Long.parseLong(next());} return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next static ArrayList<String> nextStrArray(){return myHanSpSplit(next());} nextStrArray {return myHanSpSplit(next());} return myHanSpSplit(next()); myHanSpSplit(next()) myHanSpSplit next() next static ArrayList<String> myHanSpSplit(String str){return new ArrayList<String>(Arrays.asList(str.split(" ")));} myHanSpSplit {return new ArrayList<String>(Arrays.asList(str.split(" ")));} return new ArrayList<String>(Arrays.asList(str.split(" "))); new ArrayList<String>(Arrays.asList(str.split(" "))) String str str static ArrayList<String> nextCharArray(){return mySingleSplit(next());} nextCharArray {return mySingleSplit(next());} return mySingleSplit(next()); mySingleSplit(next()) mySingleSplit next() next static ArrayList<String> mySingleSplit(String str){return new ArrayList<String>(Arrays.asList(str.split("")));} mySingleSplit {return new ArrayList<String>(Arrays.asList(str.split("")));} return new ArrayList<String>(Arrays.asList(str.split(""))); new ArrayList<String>(Arrays.asList(str.split(""))) String str str static ArrayList<Integer> nextIntArray(){
    ArrayList<Integer> ret = new ArrayList<Integer>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    }
    return ret;
  } nextIntArray {
    ArrayList<Integer> ret = new ArrayList<Integer>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    }
    return ret;
  } ArrayList<Integer> ret = new ArrayList<Integer>(); ret new ArrayList<Integer>() ArrayList<String> input = nextStrArray(); input nextStrArray() nextStrArray for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    } int i = 0; int i = 0; i 0 i < input.size() i input.size() input.size input i++ i++ i {
      ret.add(Integer.parseInt(input.get(i)));
    } {
      ret.add(Integer.parseInt(input.get(i)));
    } ret.add(Integer.parseInt(input.get(i))) ret.add ret Integer.parseInt(input.get(i)) Integer.parseInt Integer input.get(i) input.get input i return ret; ret static ArrayList<Long> nextLongArray(){
    ArrayList<Long> ret = new ArrayList<Long>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    }
    return ret;
  } nextLongArray {
    ArrayList<Long> ret = new ArrayList<Long>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    }
    return ret;
  } ArrayList<Long> ret = new ArrayList<Long>(); ret new ArrayList<Long>() ArrayList<String> input = nextStrArray(); input nextStrArray() nextStrArray for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    } int i = 0; int i = 0; i 0 i < input.size() i input.size() input.size input i++ i++ i {
      ret.add(Long.parseLong(input.get(i)));
    } {
      ret.add(Long.parseLong(input.get(i)));
    } ret.add(Long.parseLong(input.get(i))) ret.add ret Long.parseLong(input.get(i)) Long.parseLong Long input.get(i) input.get input i return ret; ret static String kaigyoToStr(String[] list){return String.join("\n",list);} kaigyoToStr {return String.join("\n",list);} return String.join("\n",list); String.join("\n",list) String.join String "\n" list String[] list list static String kaigyoToStr(ArrayList<String> list){return String.join("\n",list);} kaigyoToStr {return String.join("\n",list);} return String.join("\n",list); String.join("\n",list) String.join String "\n" list ArrayList<String> list list static String hanSpToStr(String[] list){return String.join(" ",list);} hanSpToStr {return String.join(" ",list);} return String.join(" ",list); String.join(" ",list) String.join String " " list String[] list list static String hanSpToStr(ArrayList<String> list){return String.join(" ",list);} hanSpToStr {return String.join(" ",list);} return String.join(" ",list); String.join(" ",list) String.join String " " list ArrayList<String> list list public static void main(String[] args){
    solve();
    flush();
  } main {
    solve();
    flush();
  } solve() solve flush() flush String[] args args //↑見なくていいよ！ここまで------------------------------------------
  static void solve(){//ここがメイン関数代わり
    long N = nextLong();
    String output = "";
    HashMap<Integer, String> map = new HashMap<Integer, String>();
    ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz");
    for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    }
    map.put(0,"z");
    int count = 1;
    while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    }
    myerr(N);
    myerr(count);
    while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    }
    myout(output);
  } solve {//ここがメイン関数代わり
    long N = nextLong();
    String output = "";
    HashMap<Integer, String> map = new HashMap<Integer, String>();
    ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz");
    for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    }
    map.put(0,"z");
    int count = 1;
    while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    }
    myerr(N);
    myerr(count);
    while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    }
    myout(output);
  } long N = nextLong(); N nextLong() nextLong String output = ""; output "" HashMap<Integer, String> map = new HashMap<Integer, String>(); map new HashMap<Integer, String>() ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz"); list mySingleSplit("abcdefghijklmnopqrstuvwxyz") mySingleSplit "abcdefghijklmnopqrstuvwxyz" for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    } int i = 0; int i = 0; i 0 i < list.size() i list.size() list.size list i++ i++ i {
      map.put(i + 1, list.get(i));
    } {
      map.put(i + 1, list.get(i));
    } map.put(i + 1, list.get(i)) map.put map i + 1 i 1 list.get(i) list.get list i map.put(0,"z") map.put map 0 "z" int count = 1; count 1 while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    } true {
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    } long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1); under (long)Math.pow(26,count) + (long)Math.pow(26, count - 1) (long)Math.pow(26,count) Math.pow Math 26 count (long)Math.pow(26, count - 1) Math.pow Math 26 count - 1 count 1 if(N >= under){
        count++;
      }else{
        break;
      } N >= under N under {
        count++;
      } count++ count {
        break;
      } break; myerr(N) myerr N myerr(count) myerr count while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    } N > 0 N 0 {
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    } int single = (int)(N % 26); single (int)(N % 26) N 26 if(single == 0){
        N -= 26;
      } single == 0 single 0 {
        N -= 26;
      } N -= 26 N 26 myerr(N) myerr N output = map.get(single) + output output map.get(single) + output map.get(single) map.get map single output N /= 26 N 26 myout(output) myout output static class InputIterator{
    ArrayList<String> inputLine = new ArrayList<String>(1024);
    int index = 0; int max;
    InputIterator(){
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    }
    boolean hasNext(){return (index < max);}
    String next(){
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    }
  } InputIterator ArrayList<String> inputLine = new ArrayList<String>(1024); inputLine new ArrayList<String>(1024) int index = 0; index 0 int max; max InputIterator(){
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    } InputIterator {
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      } true {
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      } String read; read try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        } catch(IOException e){
          read = null;
        } IOException e {
          read = null;
        } read = null read null {
          read = br.readLine();
        } read = br.readLine() read br.readLine() br.readLine br if(read != null){
          inputLine.add(read);
        }else{
          break;
        } read != null read null {
          inputLine.add(read);
        } inputLine.add(read) inputLine.add inputLine read {
          break;
        } break; max = inputLine.size() max inputLine.size() inputLine.size inputLine boolean hasNext(){return (index < max);} hasNext {return (index < max);} return (index < max); (index < max) index max String next(){
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    } next {
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    } if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      } hasNext() hasNext {
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      } String returnStr = inputLine.get(index); returnStr inputLine.get(index) inputLine.get inputLine index index++ index return returnStr; returnStr {
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      } throw new IndexOutOfBoundsException("これ以上入力はないよ"); new IndexOutOfBoundsException("これ以上入力はないよ") public class Main{
  //↓見なくていいよ！ここから------------------------------------------
  static class InputIterator{
    ArrayList<String> inputLine = new ArrayList<String>(1024);
    int index = 0; int max;
    InputIterator(){
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    }
    boolean hasNext(){return (index < max);}
    String next(){
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    }
  }
  
  static InputIterator ii = new InputIterator();//リアクティブでは使えないので諦めてScanner使うこと
  static PrintWriter out = new PrintWriter(System.out);
  static void flush(){out.flush();}
  static void myout(Object t){out.println(t);}
  static void myerr(Object t){System.err.println(t);}
  static String next(){return ii.next();}
  static int nextInt(){return Integer.parseInt(next());}
  static long nextLong(){return Long.parseLong(next());}
  static ArrayList<String> nextStrArray(){return myHanSpSplit(next());}
  static ArrayList<String> myHanSpSplit(String str){return new ArrayList<String>(Arrays.asList(str.split(" ")));}
  static ArrayList<String> nextCharArray(){return mySingleSplit(next());}
  static ArrayList<String> mySingleSplit(String str){return new ArrayList<String>(Arrays.asList(str.split("")));}
  static ArrayList<Integer> nextIntArray(){
    ArrayList<Integer> ret = new ArrayList<Integer>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    }
    return ret;
  }
  static ArrayList<Long> nextLongArray(){
    ArrayList<Long> ret = new ArrayList<Long>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    }
    return ret;
  }
  static String kaigyoToStr(String[] list){return String.join("\n",list);}
  static String kaigyoToStr(ArrayList<String> list){return String.join("\n",list);}
  static String hanSpToStr(String[] list){return String.join(" ",list);}
  static String hanSpToStr(ArrayList<String> list){return String.join(" ",list);}
  public static void main(String[] args){
    solve();
    flush();
  }
  //↑見なくていいよ！ここまで------------------------------------------
  static void solve(){//ここがメイン関数代わり
    long N = nextLong();
    String output = "";
    HashMap<Integer, String> map = new HashMap<Integer, String>();
    ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz");
    for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    }
    map.put(0,"z");
    int count = 1;
    while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    }
    myerr(N);
    myerr(count);
    while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    }
    myout(output);
  }
  //Method addition frame start

  //Method addition frame end
} public class Main{
  //↓見なくていいよ！ここから------------------------------------------
  static class InputIterator{
    ArrayList<String> inputLine = new ArrayList<String>(1024);
    int index = 0; int max;
    InputIterator(){
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    }
    boolean hasNext(){return (index < max);}
    String next(){
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    }
  }
  
  static InputIterator ii = new InputIterator();//リアクティブでは使えないので諦めてScanner使うこと
  static PrintWriter out = new PrintWriter(System.out);
  static void flush(){out.flush();}
  static void myout(Object t){out.println(t);}
  static void myerr(Object t){System.err.println(t);}
  static String next(){return ii.next();}
  static int nextInt(){return Integer.parseInt(next());}
  static long nextLong(){return Long.parseLong(next());}
  static ArrayList<String> nextStrArray(){return myHanSpSplit(next());}
  static ArrayList<String> myHanSpSplit(String str){return new ArrayList<String>(Arrays.asList(str.split(" ")));}
  static ArrayList<String> nextCharArray(){return mySingleSplit(next());}
  static ArrayList<String> mySingleSplit(String str){return new ArrayList<String>(Arrays.asList(str.split("")));}
  static ArrayList<Integer> nextIntArray(){
    ArrayList<Integer> ret = new ArrayList<Integer>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    }
    return ret;
  }
  static ArrayList<Long> nextLongArray(){
    ArrayList<Long> ret = new ArrayList<Long>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    }
    return ret;
  }
  static String kaigyoToStr(String[] list){return String.join("\n",list);}
  static String kaigyoToStr(ArrayList<String> list){return String.join("\n",list);}
  static String hanSpToStr(String[] list){return String.join(" ",list);}
  static String hanSpToStr(ArrayList<String> list){return String.join(" ",list);}
  public static void main(String[] args){
    solve();
    flush();
  }
  //↑見なくていいよ！ここまで------------------------------------------
  static void solve(){//ここがメイン関数代わり
    long N = nextLong();
    String output = "";
    HashMap<Integer, String> map = new HashMap<Integer, String>();
    ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz");
    for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    }
    map.put(0,"z");
    int count = 1;
    while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    }
    myerr(N);
    myerr(count);
    while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    }
    myout(output);
  }
  //Method addition frame start

  //Method addition frame end
} Main
import java.util.*;import java.io.*;import java.math.*;
public class Main{
  //↓見なくていいよ！ここから------------------------------------------
  static class InputIterator{
    ArrayList<String> inputLine = new ArrayList<String>(1024);
    int index = 0; int max;
    InputIterator(){
      BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
      while(true){
        String read;
        try{
          read = br.readLine();
        }catch(IOException e){
          read = null;
        }
        if(read != null){
          inputLine.add(read);
        }else{
          break;
        }
      }
      max = inputLine.size();
    }
    boolean hasNext(){return (index < max);}
    String next(){
      if(hasNext()){
        String returnStr = inputLine.get(index);
        index++;
        return returnStr;
      }else{
        throw new IndexOutOfBoundsException("これ以上入力はないよ");
      }
    }
  }
  
  static InputIterator ii = new InputIterator();//リアクティブでは使えないので諦めてScanner使うこと
  static PrintWriter out = new PrintWriter(System.out);
  static void flush(){out.flush();}
  static void myout(Object t){out.println(t);}
  static void myerr(Object t){System.err.println(t);}
  static String next(){return ii.next();}
  static int nextInt(){return Integer.parseInt(next());}
  static long nextLong(){return Long.parseLong(next());}
  static ArrayList<String> nextStrArray(){return myHanSpSplit(next());}
  static ArrayList<String> myHanSpSplit(String str){return new ArrayList<String>(Arrays.asList(str.split(" ")));}
  static ArrayList<String> nextCharArray(){return mySingleSplit(next());}
  static ArrayList<String> mySingleSplit(String str){return new ArrayList<String>(Arrays.asList(str.split("")));}
  static ArrayList<Integer> nextIntArray(){
    ArrayList<Integer> ret = new ArrayList<Integer>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Integer.parseInt(input.get(i)));
    }
    return ret;
  }
  static ArrayList<Long> nextLongArray(){
    ArrayList<Long> ret = new ArrayList<Long>();
    ArrayList<String> input = nextStrArray();
    for(int i = 0; i < input.size(); i++){
      ret.add(Long.parseLong(input.get(i)));
    }
    return ret;
  }
  static String kaigyoToStr(String[] list){return String.join("\n",list);}
  static String kaigyoToStr(ArrayList<String> list){return String.join("\n",list);}
  static String hanSpToStr(String[] list){return String.join(" ",list);}
  static String hanSpToStr(ArrayList<String> list){return String.join(" ",list);}
  public static void main(String[] args){
    solve();
    flush();
  }
  //↑見なくていいよ！ここまで------------------------------------------
  static void solve(){//ここがメイン関数代わり
    long N = nextLong();
    String output = "";
    HashMap<Integer, String> map = new HashMap<Integer, String>();
    ArrayList<String> list = mySingleSplit("abcdefghijklmnopqrstuvwxyz");
    for(int i = 0; i < list.size(); i++){
      map.put(i + 1, list.get(i));
    }
    map.put(0,"z");
    int count = 1;
    while(true){
      long under = (long)Math.pow(26,count) + (long)Math.pow(26, count - 1);
      if(N >= under){
        count++;
      }else{
        break;
      }
    }
    myerr(N);
    myerr(count);
    while(N > 0){
      int single = (int)(N % 26);
      //myerr(single);
      if(single == 0){
        N -= 26;
      }
      myerr(N);
      output = map.get(single) + output;
      N /= 26;
    }
    myout(output);
  }
  //Method addition frame start

  //Method addition frame end
}
