Alphabet palindrome pyramid

Problem

Print a centred pyramid of letters with n rows. Row i has n - i spaces, then the letters from A up to the i-th letter, then back down to A:

`` A ABA ABCBA ``

Example

Input

Output

   A
  ABA
 ABCBA
ABCDCBA

The last row is ABCDCBA.

Try the problem first. Open one hint at a time.

Hint 1

Each row has three parts: spaces, letters going up, letters going down.

Hint 2

Going up, print A to the i-th letter. Going down, start one letter below the top so it is not printed twice.

Hint 3

Use a char loop variable: for (char c = 'A'; c < 'A' + i; c++).

Write your Java code, run it on the examples and submit it to hidden tests.