import java.util.Scanner;

public class Main {

	public static long N;

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		N = scan.nextLong();
		String S = judge(N % 26);
		N /= 26;
		int i = 1;

		while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		}

		System.out.println(S);
	}

	public static String judge(long x) {

		switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		}

		return "";
	}

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

	public static long N;

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		N = scan.nextLong();
		String S = judge(N % 26);
		N /= 26;
		int i = 1;

		while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		}

		System.out.println(S);
	}

	public static String judge(long x) {

		switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		}

		return "";
	}

} Main public static long N; N public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		N = scan.nextLong();
		String S = judge(N % 26);
		N /= 26;
		int i = 1;

		while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		}

		System.out.println(S);
	} main {

		Scanner scan = new Scanner(System.in);

		N = scan.nextLong();
		String S = judge(N % 26);
		N /= 26;
		int i = 1;

		while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		}

		System.out.println(S);
	} Scanner scan = new Scanner(System.in); scan new Scanner(System.in) N = scan.nextLong() N scan.nextLong() scan.nextLong scan String S = judge(N % 26); S judge(N % 26) judge N % 26 N 26 N /= 26 N 26 int i = 1; i 1 while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		} N != 0 N 0 {
			S = judge(N % 26) + S;
			N /= 26;

		} S = judge(N % 26) + S S judge(N % 26) + S judge(N % 26) judge N % 26 N 26 S N /= 26 N 26 System.out.println(S) System.out.println System.out System System.out S String[] args args public static String judge(long x) {

		switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		}

		return "";
	} judge {

		switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		}

		return "";
	} switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		} (int)x case 1: 1 case 1: return "a"; "a" case 2: 2 case 2: return "b"; "b" case 3: 3 case 3: return "c"; "c" case 4: 4 case 4: return "d"; "d" case 5: 5 case 5: return "e"; "e" case 6: 6 case 6: return "f"; "f" case 7: 7 case 7: return "g"; "g" case 8: 8 case 8: return "h"; "h" case 9: 9 case 9: return "i"; "i" case 10: 10 case 10: return "j"; "j" case 11: 11 case 11: return "k"; "k" case 12: 12 case 12: return "l"; "l" case 13: 13 case 13: return "m"; "m" case 14: 14 case 14: return "n"; "n" case 15: 15 case 15: return "o"; "o" case 16: 16 case 16: return "p"; "p" case 17: 17 case 17: return "q"; "q" case 18: 18 case 18: return "r"; "r" case 19: 19 case 19: return "s"; "s" case 20: 20 case 20: return "t"; "t" case 21: 21 case 21: return "u"; "u" case 22: 22 case 22: return "v"; "v" case 23: 23 case 23: return "w"; "w" case 24: 24 case 24: return "x"; "x" case 25: 25 case 25: return "y"; "y" case 0: 0 case 0: N -= 1 N 1 return "z"; "z" return ""; "" long x x public class Main {

	public static long N;

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		N = scan.nextLong();
		String S = judge(N % 26);
		N /= 26;
		int i = 1;

		while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		}

		System.out.println(S);
	}

	public static String judge(long x) {

		switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		}

		return "";
	}

} public class Main {

	public static long N;

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		N = scan.nextLong();
		String S = judge(N % 26);
		N /= 26;
		int i = 1;

		while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		}

		System.out.println(S);
	}

	public static String judge(long x) {

		switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		}

		return "";
	}

} Main
import java.util.Scanner;

public class Main {

	public static long N;

	public static void main(String[] args) {

		Scanner scan = new Scanner(System.in);

		N = scan.nextLong();
		String S = judge(N % 26);
		N /= 26;
		int i = 1;

		while (N != 0) {
			S = judge(N % 26) + S;
			N /= 26;

		}

		System.out.println(S);
	}

	public static String judge(long x) {

		switch ((int)x) {
		case 1:
			return "a";
		case 2:
			return "b";
		case 3:
			return "c";
		case 4:
			return "d";
		case 5:
			return "e";
		case 6:
			return "f";
		case 7:
			return "g";
		case 8:
			return "h";
		case 9:
			return "i";
		case 10:
			return "j";
		case 11:
			return "k";
		case 12:
			return "l";
		case 13:
			return "m";
		case 14:
			return "n";
		case 15:
			return "o";
		case 16:
			return "p";
		case 17:
			return "q";
		case 18:
			return "r";
		case 19:
			return "s";
		case 20:
			return "t";
		case 21:
			return "u";
		case 22:
			return "v";
		case 23:
			return "w";
		case 24:
			return "x";
		case 25:
			return "y";
		case 0:
			 N -= 1;
			return "z";
		}

		return "";
	}

}