import java.util.*;

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

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