import java.util.Scanner;

public class Main {

	static long mod = 1000000007;
	static long INF = Long.MAX_VALUE;

	static long chmin(long a, long b) {
		return Math.min(a, b);
	}

	static long chmax(long a, long b) {
		return Math.max(a, b);
	}

	public static void main(String[] args) {
		// AtCoder_C
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
	    // Scannerクラスのインスタンスをクローズ
		sc.close();

		String ans = "";

		while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		}

		System.out.print(ans);
	}
} import java.util.Scanner; Scanner java.util public class Main {

	static long mod = 1000000007;
	static long INF = Long.MAX_VALUE;

	static long chmin(long a, long b) {
		return Math.min(a, b);
	}

	static long chmax(long a, long b) {
		return Math.max(a, b);
	}

	public static void main(String[] args) {
		// AtCoder_C
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
	    // Scannerクラスのインスタンスをクローズ
		sc.close();

		String ans = "";

		while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		}

		System.out.print(ans);
	}
} Main static long mod = 1000000007; mod 1000000007 static long INF = Long.MAX_VALUE; INF Long.MAX_VALUE Long Long.MAX_VALUE static long chmin(long a, long b) {
		return Math.min(a, b);
	} chmin {
		return Math.min(a, b);
	} return Math.min(a, b); Math.min(a, b) Math.min Math a b long a a long b b static long chmax(long a, long b) {
		return Math.max(a, b);
	} chmax {
		return Math.max(a, b);
	} return Math.max(a, b); Math.max(a, b) Math.max Math a b long a a long b b public static void main(String[] args) {
		// AtCoder_C
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
	    // Scannerクラスのインスタンスをクローズ
		sc.close();

		String ans = "";

		while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		}

		System.out.print(ans);
	} main {
		// AtCoder_C
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
	    // Scannerクラスのインスタンスをクローズ
		sc.close();

		String ans = "";

		while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		}

		System.out.print(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 ans = ""; ans "" while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		} N>0 N 0 {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		} N -= 1 N 1 ans = (char)('a'+(N%26)) + ans ans (char)('a'+(N%26)) + ans (char)('a'+(N%26)) 'a' (N%26) N 26 ans N /= 26 N 26 System.out.print(ans) System.out.print System.out System System.out ans String[] args args public class Main {

	static long mod = 1000000007;
	static long INF = Long.MAX_VALUE;

	static long chmin(long a, long b) {
		return Math.min(a, b);
	}

	static long chmax(long a, long b) {
		return Math.max(a, b);
	}

	public static void main(String[] args) {
		// AtCoder_C
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
	    // Scannerクラスのインスタンスをクローズ
		sc.close();

		String ans = "";

		while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		}

		System.out.print(ans);
	}
} public class Main {

	static long mod = 1000000007;
	static long INF = Long.MAX_VALUE;

	static long chmin(long a, long b) {
		return Math.min(a, b);
	}

	static long chmax(long a, long b) {
		return Math.max(a, b);
	}

	public static void main(String[] args) {
		// AtCoder_C
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
	    // Scannerクラスのインスタンスをクローズ
		sc.close();

		String ans = "";

		while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		}

		System.out.print(ans);
	}
} Main
import java.util.Scanner;

public class Main {

	static long mod = 1000000007;
	static long INF = Long.MAX_VALUE;

	static long chmin(long a, long b) {
		return Math.min(a, b);
	}

	static long chmax(long a, long b) {
		return Math.max(a, b);
	}

	public static void main(String[] args) {
		// AtCoder_C
		Scanner sc = new Scanner(System.in);
		long N = sc.nextLong();
	    // Scannerクラスのインスタンスをクローズ
		sc.close();

		String ans = "";

		while (N>0) {
			N -= 1;
			ans = (char)('a'+(N%26)) + ans;
			N /= 26;
		}

		System.out.print(ans);
	}
}