import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.io.PrintStream; import java.io.PrintWriter; import java.util.ArrayDeque; import java.util.Arrays; import java.util.Deque; import java.util.Iterator; public class Main_yukicoder327 { public static void main(String[] args) { Scanner sc = new Scanner(System.in); Printer pr = new Printer(System.out); char[] a = new char[26]; for (char c = 'A'; c <= 'Z'; c++) { a[c - 'A'] = c; } long n = sc.nextLong(); Deque st = new ArrayDeque(); st.push(a[(int)(n % 26)]); n /= 26; while (n > 0) { st.push(a[(int)(n % 26 - 1)]); n /= 26; } for (char c : st) { pr.print(c); } pr.println(); pr.close(); sc.close(); } @SuppressWarnings("unused") private static class Scanner { BufferedReader br; Iterator it; Scanner (InputStream in) { br = new BufferedReader(new InputStreamReader(in)); } String next() throws RuntimeException { try { if (it == null || !it.hasNext()) { it = Arrays.asList(br.readLine().split(" ")).iterator(); } return it.next(); } catch (IOException e) { throw new IllegalStateException(); } } int nextInt() throws RuntimeException { return Integer.parseInt(next()); } long nextLong() throws RuntimeException { return Long.parseLong(next()); } float nextFloat() throws RuntimeException { return Float.parseFloat(next()); } double nextDouble() throws RuntimeException { return Double.parseDouble(next()); } void close() { try { br.close(); } catch (IOException e) { // throw new IllegalStateException(); } } } private static class Printer extends PrintWriter { Printer(PrintStream out) { super(out); } } }