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

public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        long n = Long.parseLong(br.readLine());
        
        br.close();

        StringBuilder ans = new StringBuilder();

        while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        }
        
        ans.reverse();
        
        bw.write(ans.toString());

        bw.flush();

    }
} import java.io.BufferedReader; BufferedReader java.io import java.io.BufferedWriter; BufferedWriter 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 Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        long n = Long.parseLong(br.readLine());
        
        br.close();

        StringBuilder ans = new StringBuilder();

        while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        }
        
        ans.reverse();
        
        bw.write(ans.toString());

        bw.flush();

    }
} Main public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        long n = Long.parseLong(br.readLine());
        
        br.close();

        StringBuilder ans = new StringBuilder();

        while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        }
        
        ans.reverse();
        
        bw.write(ans.toString());

        bw.flush();

    } main {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        long n = Long.parseLong(br.readLine());
        
        br.close();

        StringBuilder ans = new StringBuilder();

        while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        }
        
        ans.reverse();
        
        bw.write(ans.toString());

        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 n = Long.parseLong(br.readLine()); n Long.parseLong(br.readLine()) Long.parseLong Long br.readLine() br.readLine br br.close() br.close br StringBuilder ans = new StringBuilder(); ans new StringBuilder() while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        } n > 0 n 0 {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        } n-- n ans.append((char)('a' + n % 26)) ans.append ans (char)('a' + n % 26) 'a' n % 26 n 26 n /= 26 n 26 ans.reverse() ans.reverse ans bw.write(ans.toString()) bw.write bw ans.toString() ans.toString ans bw.flush() bw.flush bw String[] args args public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        long n = Long.parseLong(br.readLine());
        
        br.close();

        StringBuilder ans = new StringBuilder();

        while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        }
        
        ans.reverse();
        
        bw.write(ans.toString());

        bw.flush();

    }
} public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        long n = Long.parseLong(br.readLine());
        
        br.close();

        StringBuilder ans = new StringBuilder();

        while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        }
        
        ans.reverse();
        
        bw.write(ans.toString());

        bw.flush();

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

public class Main {
    public static void main(String[] args) throws Exception {

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        long n = Long.parseLong(br.readLine());
        
        br.close();

        StringBuilder ans = new StringBuilder();

        while (n > 0) {
            n--;
            ans.append((char)('a' + n % 26));
            n /= 26;
        }
        
        ans.reverse();
        
        bw.write(ans.toString());

        bw.flush();

    }
}