import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		long N = sc.nextLong() - 1;
		LinkedList<Integer> stack = new LinkedList<>();
		while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		}
		while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		}
	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} import java.util.*; util.* java public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		long N = sc.nextLong() - 1;
		LinkedList<Integer> stack = new LinkedList<>();
		while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		}
		while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		}
	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} Main Scanner sc = new Scanner(System.in); sc new Scanner(System.in) final int MOD = 998244353; MOD 998244353 final int MAX = Integer.MAX_VALUE; MAX Integer.MAX_VALUE Integer Integer.MAX_VALUE final long LMAX = Long.MAX_VALUE; LMAX Long.MAX_VALUE Long Long.MAX_VALUE long inf = LMAX / 2 - MAX; inf LMAX / 2 - MAX LMAX / 2 LMAX 2 MAX void doIt() {
		long N = sc.nextLong() - 1;
		LinkedList<Integer> stack = new LinkedList<>();
		while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		}
		while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		}
	} doIt {
		long N = sc.nextLong() - 1;
		LinkedList<Integer> stack = new LinkedList<>();
		while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		}
		while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		}
	} long N = sc.nextLong() - 1; N sc.nextLong() - 1 sc.nextLong() sc.nextLong sc 1 LinkedList<Integer> stack = new LinkedList<>(); stack new LinkedList<>() while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		} N >= 0 N 0 {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		} stack.push((int)(N % 26)) stack.push stack (int)(N % 26) N 26 N -= 26 N 26 if(N < 0) break; N < 0 N 0 break; N /= 26 N 26 while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		} !stack.isEmpty() stack.isEmpty() stack.isEmpty stack {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		} int c = stack.pollFirst(); c stack.pollFirst() stack.pollFirst stack System.out.print((char)(c + 'a')) System.out.print System.out System System.out (char)(c + 'a') c 'a' public static void main(String[] args) {
		new Main().doIt();
	} main {
		new Main().doIt();
	} new Main().doIt() new Main().doIt new Main() String[] args args public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		long N = sc.nextLong() - 1;
		LinkedList<Integer> stack = new LinkedList<>();
		while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		}
		while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		}
	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		long N = sc.nextLong() - 1;
		LinkedList<Integer> stack = new LinkedList<>();
		while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		}
		while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		}
	}

	public static void main(String[] args) {
		new Main().doIt();
	}
} Main
import java.util.*;

public class Main {
	Scanner sc = new Scanner(System.in);
	final int MOD = 998244353;
	final int MAX = Integer.MAX_VALUE;
	final long LMAX = Long.MAX_VALUE;
	long inf = LMAX / 2 - MAX;

	void doIt() {
		long N = sc.nextLong() - 1;
		LinkedList<Integer> stack = new LinkedList<>();
		while(N >= 0) {
			stack.push((int)(N % 26));
			N -= 26;
			if(N < 0) break;
			N /= 26;
		}
		while(!stack.isEmpty()) {
			int c = stack.pollFirst();
			System.out.print((char)(c + 'a'));
		}
	}

	public static void main(String[] args) {
		new Main().doIt();
	}
}
