Add Forth solution

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+#! /usr/bin/env gforth
+
+\ Challenge 205
+\
+\ Task 2: Maximum XOR
+\ Submitted by: Mohammad S Anwar
+\
+\ You are given an array of integers.
+\
+\ Write a script to find the highest value obtained by XORing any two distinct members of the array.
+\ Example 1
+\
+\ Input: @array = (1,2,3,4,5,6,7)
+\ Output: 7
+\
+\ The maximum result of 1 xor 6 = 7.
+\
+\ Example 2
+\
+\ Input: @array = (2,4,1,3)
+\ Output: 7
+\
+\ The maximum result of 4 xor 3 = 7.
+\
+\ Example 3
+\
+\ Input: @array = (10,5,7,12,8)
+\ Output: 15
+\
+\ The maximum result of 10 xor 5 = 15.
+
+
+\ array of numbers, setup by collect-args
+0 VALUE items                       \ array of numbers
+0 VALUE num_items                   \ number of elements
+
+: items[] ( i -- addr )
+    CELLS items +
+;
+
+
+\ collect arguments from input and store in items
+: collect_args ( -- )
+    HERE TO items
+    BEGIN NEXT-ARG DUP WHILE        \ while argments
+        0 0 2SWAP >NUMBER 2DROP DROP ,
+    REPEAT
+    2DROP
+    HERE items - CELL / TO num_items
+;
+
+
+\ compute max of XOR of all pairs
+: max_xor ( -- n )
+    0                               ( max )
+    num_items 1 > IF
+        num_items 1-  0  DO
+            num_items  I 1+  DO
+                I items[] @
+                J items[] @  XOR  MAX
+            LOOP
+        LOOP
+    THEN
+;
+
+
+collect_args max_xor . CR
+BYE