import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		String[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

		String ans = "";

		while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		}
		System.out.println(ans);



	}
} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		String[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

		String ans = "";

		while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		}
		System.out.println(ans);



	}
} Main public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		String[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

		String ans = "";

		while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		}
		System.out.println(ans);



	} main {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		String[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

		String ans = "";

		while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		}
		System.out.println(ans);



	} 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[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"}; list {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"} "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" String ans = ""; ans "" while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		} n>0 n 0 {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		} long m = n%26L; m n%26L n 26L if(m==0) {
				m = 26L;
			} m==0 m 0 {
				m = 26L;
			} m = 26L m 26L ans = list[(int) (m-1)]+ans ans list[(int) (m-1)]+ans list[(int) (m-1)] list (int) (m-1) m 1 ans n = (n-m)/26L n (n-m)/26L (n-m) n m 26L 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) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		String[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

		String ans = "";

		while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		}
		System.out.println(ans);



	}
} public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		String[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

		String ans = "";

		while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		}
		System.out.println(ans);



	}
} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		sc.close();

		String[] list = {"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};

		String ans = "";

		while(n>0) {
			long m = n%26L;
			if(m==0) {
				m = 26L;
			}
			ans = list[(int) (m-1)]+ans;
			n = (n-m)/26L;
		}
		System.out.println(ans);



	}
}
