import java.io.*;
public class Main{
    public static void main(String args[]) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        out.println(go(Long.parseLong(br.readLine().trim())));
        out.flush();
    }
    public static String go(long n){
        if(n==0) return "";
        --n;
        return go(n/26)+((char)('a'+(n%26)));
    }
} import java.io.*; io.* java public class Main{
    public static void main(String args[]) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        out.println(go(Long.parseLong(br.readLine().trim())));
        out.flush();
    }
    public static String go(long n){
        if(n==0) return "";
        --n;
        return go(n/26)+((char)('a'+(n%26)));
    }
} Main public static void main(String args[]) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        out.println(go(Long.parseLong(br.readLine().trim())));
        out.flush();
    } main {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        out.println(go(Long.parseLong(br.readLine().trim())));
        out.flush();
    } BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); br new BufferedReader(new InputStreamReader(System.in)) PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out)); out new PrintWriter(new OutputStreamWriter(System.out)) out.println(go(Long.parseLong(br.readLine().trim()))) out.println out go(Long.parseLong(br.readLine().trim())) go Long.parseLong(br.readLine().trim()) Long.parseLong Long br.readLine().trim() br.readLine().trim br.readLine() br.readLine br out.flush() out.flush out String args[] args public static String go(long n){
        if(n==0) return "";
        --n;
        return go(n/26)+((char)('a'+(n%26)));
    } go {
        if(n==0) return "";
        --n;
        return go(n/26)+((char)('a'+(n%26)));
    } if(n==0) return ""; n==0 n 0 return ""; "" --n n return go(n/26)+((char)('a'+(n%26))); go(n/26)+((char)('a'+(n%26))) go(n/26) go n/26 n 26 ((char)('a'+(n%26))) 'a' (n%26) n 26 long n n public class Main{
    public static void main(String args[]) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        out.println(go(Long.parseLong(br.readLine().trim())));
        out.flush();
    }
    public static String go(long n){
        if(n==0) return "";
        --n;
        return go(n/26)+((char)('a'+(n%26)));
    }
} public class Main{
    public static void main(String args[]) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        out.println(go(Long.parseLong(br.readLine().trim())));
        out.flush();
    }
    public static String go(long n){
        if(n==0) return "";
        --n;
        return go(n/26)+((char)('a'+(n%26)));
    }
} Main
import java.io.*;
public class Main{
    public static void main(String args[]) throws Exception{
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));
        out.println(go(Long.parseLong(br.readLine().trim())));
        out.flush();
    }
    public static String go(long n){
        if(n==0) return "";
        --n;
        return go(n/26)+((char)('a'+(n%26)));
    }
}