import java.util.*;

class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
		sc.close();
		int tmp;
		String ans = "";
		while (N > 0){
			N-=1;
			tmp = (int) (N % 26);
			ans += (char)(tmp + 'a');
			N /= 26;
		}
		for(int i=ans.length();i>0;--i){
			System.out.print(ans.charAt(i-1));
		}
	}
} import java.util.*; util.* java class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
		sc.close();
		int tmp;
		String ans = "";
		while (N > 0){
			N-=1;
			tmp = (int) (N % 26);
			ans += (char)(tmp + 'a');
			N /= 26;
		}
		for(int i=ans.length();i>0;--i){
			System.out.print(ans.charAt(i-1));
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
		sc.close();
		int tmp;
		String ans = "";
		while (N > 0){
			N-=1;
			tmp = (int) (N % 26);
			ans += (char)(tmp + 'a');
			N /= 26;
		}
		for(int i=ans.length();i>0;--i){
			System.out.print(ans.charAt(i-1));
		}
	} main {
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
		sc.close();
		int tmp;
		String ans = "";
		while (N > 0){
			N-=1;
			tmp = (int) (N % 26);
			ans += (char)(tmp + 'a');
			N /= 26;
		}
		for(int i=ans.length();i>0;--i){
			System.out.print(ans.charAt(i-1));
		}
	} 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 int tmp; tmp String ans = ""; ans "" while (N > 0){
			N-=1;
			tmp = (int) (N % 26);
			ans += (char)(tmp + 'a');
			N /= 26;
		} N > 0 N 0 {
			N-=1;
			tmp = (int) (N % 26);
			ans += (char)(tmp + 'a');
			N /= 26;
		} N-=1 N 1 tmp = (int) (N % 26) tmp (int) (N % 26) N 26 ans += (char)(tmp + 'a') ans (char)(tmp + 'a') tmp 'a' N /= 26 N 26 for(int i=ans.length();i>0;--i){
			System.out.print(ans.charAt(i-1));
		} int i=ans.length(); int i=ans.length(); i ans.length() ans.length ans i>0 i 0 --i --i i {
			System.out.print(ans.charAt(i-1));
		} {
			System.out.print(ans.charAt(i-1));
		} System.out.print(ans.charAt(i-1)) System.out.print System.out System System.out ans.charAt(i-1) ans.charAt ans i-1 i 1 String[] args args
import java.util.*;

class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
		sc.close();
		int tmp;
		String ans = "";
		while (N > 0){
			N-=1;
			tmp = (int) (N % 26);
			ans += (char)(tmp + 'a');
			N /= 26;
		}
		for(int i=ans.length();i>0;--i){
			System.out.print(ans.charAt(i-1));
		}
	}
}
