Base.java

import java.util.Scanner;

public final class Base {

   // Digits:  A=0, B=1, ...., Z=25
   public static final int BASE = 26;

   public static void main (final String[] args) {
      final Scanner stdin = new Scanner(System.in);
      while (stdin.hasNextInt()) {
         final int n = stdin.nextInt();
         assert 0<=n && n<BASE;
         final StringBuilder sb = new StringBuilder(7);
         int x=n;
         do {
            final int cp = 'A' + x%BASE; // unicode code point in BMP
            assert (Character.isBmpCodePoint (cp));
               
            // 0="A", 1="B", ..., 25="Z"
            sb.appendCodePoint (cp);  // insert at the end
            x /= BASE;
         } while (x>0);
         System.out.format ("%d = %s base %d%n", n, sb.reverse(), BASE);
      }
   }
}