import java.util.*;

class Main {
    public static void main(String[] args) throws Exception{
	    Scanner sc = new Scanner(System.in);
		long N=sc.nextLong();
		sc.close();
		String t="";
		while(N>0){
		    N--;
		    t+=(char)('a'+N%26);
		    N/=26;
		}
		for(int i=t.length()-1;i>=0;i--) {
			System.out.print(t.charAt(i));
		}
	}
} import java.util.*; util.* java class Main {
    public static void main(String[] args) throws Exception{
	    Scanner sc = new Scanner(System.in);
		long N=sc.nextLong();
		sc.close();
		String t="";
		while(N>0){
		    N--;
		    t+=(char)('a'+N%26);
		    N/=26;
		}
		for(int i=t.length()-1;i>=0;i--) {
			System.out.print(t.charAt(i));
		}
	}
} Main public static void main(String[] args) throws Exception{
	    Scanner sc = new Scanner(System.in);
		long N=sc.nextLong();
		sc.close();
		String t="";
		while(N>0){
		    N--;
		    t+=(char)('a'+N%26);
		    N/=26;
		}
		for(int i=t.length()-1;i>=0;i--) {
			System.out.print(t.charAt(i));
		}
	} main {
	    Scanner sc = new Scanner(System.in);
		long N=sc.nextLong();
		sc.close();
		String t="";
		while(N>0){
		    N--;
		    t+=(char)('a'+N%26);
		    N/=26;
		}
		for(int i=t.length()-1;i>=0;i--) {
			System.out.print(t.charAt(i));
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) long N=sc.nextLong(); N sc.nextLong() sc.nextLong sc sc.close() sc.close sc String t=""; t "" while(N>0){
		    N--;
		    t+=(char)('a'+N%26);
		    N/=26;
		} N>0 N 0 {
		    N--;
		    t+=(char)('a'+N%26);
		    N/=26;
		} N-- N t+=(char)('a'+N%26) t (char)('a'+N%26) 'a' N%26 N 26 N/=26 N 26 for(int i=t.length()-1;i>=0;i--) {
			System.out.print(t.charAt(i));
		} int i=t.length()-1; int i=t.length()-1; i t.length()-1 t.length() t.length t 1 i>=0 i 0 i-- i-- i {
			System.out.print(t.charAt(i));
		} {
			System.out.print(t.charAt(i));
		} System.out.print(t.charAt(i)) System.out.print System.out System System.out t.charAt(i) t.charAt t i String[] args args
import java.util.*;

class Main {
    public static void main(String[] args) throws Exception{
	    Scanner sc = new Scanner(System.in);
		long N=sc.nextLong();
		sc.close();
		String t="";
		while(N>0){
		    N--;
		    t+=(char)('a'+N%26);
		    N/=26;
		}
		for(int i=t.length()-1;i>=0;i--) {
			System.out.print(t.charAt(i));
		}
	}
}
