import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		long dog = Long.parseLong(br.readLine());
		String res = "";
		
		while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		}
		
		bw.write(res + "\n");
		bw.flush();
	}

} import java.io.BufferedReader; BufferedReader java.io import java.io.BufferedWriter; BufferedWriter java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.OutputStreamWriter; OutputStreamWriter java.io public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		long dog = Long.parseLong(br.readLine());
		String res = "";
		
		while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		}
		
		bw.write(res + "\n");
		bw.flush();
	}

} Main public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		long dog = Long.parseLong(br.readLine());
		String res = "";
		
		while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		}
		
		bw.write(res + "\n");
		bw.flush();
	} main {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		long dog = Long.parseLong(br.readLine());
		String res = "";
		
		while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		}
		
		bw.write(res + "\n");
		bw.flush();
	} BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out)); bw new BufferedWriter(new OutputStreamWriter(System.out)) long dog = Long.parseLong(br.readLine()); dog Long.parseLong(br.readLine()) Long.parseLong Long br.readLine() br.readLine br String res = ""; res "" while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		} dog-- > 0 dog-- dog 0 {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		} res = (char)('a' + (dog%26)) + res res (char)('a' + (dog%26)) + res (char)('a' + (dog%26)) 'a' (dog%26) dog 26 res dog /= 26 dog 26 bw.write(res + "\n") bw.write bw res + "\n" res "\n" bw.flush() bw.flush bw String[] args args public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		long dog = Long.parseLong(br.readLine());
		String res = "";
		
		while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		}
		
		bw.write(res + "\n");
		bw.flush();
	}

} public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		long dog = Long.parseLong(br.readLine());
		String res = "";
		
		while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		}
		
		bw.write(res + "\n");
		bw.flush();
	}

} Main
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		
		long dog = Long.parseLong(br.readLine());
		String res = "";
		
		while(dog-- > 0) {
			res = (char)('a' + (dog%26)) + res;
			dog /= 26;
		}
		
		bw.write(res + "\n");
		bw.flush();
	}

}
