*** Input: abbaca
Remove 'bb' => 'aaca'
Remove 'aa' => 'ca'
Expected Output : 'ca'
Got Output : 'ca'
ok 1 - 'abbaca' ->'ca'
...

*** Input: azxxzy
Remove 'xx' => 'azzy'
Remove 'zz' => 'ay'
Expected Output : 'ay'
Got Output : 'ay'
ok 2 - 'azxxzy' ->'ay'
...

*** Input: aaaaaaaa
Remove 'aa' => 'aaaaaa'
Remove 'aa' => 'aaaa'
Remove 'aa' => 'aa'
Remove 'aa' => ''
Expected Output : ''
Got Output : ''
ok 3 - 'aaaaaaaa' ->''
...

*** Input: aabccba
Remove 'aa' => 'bccba'
Remove 'cc' => 'bba'
Remove 'bb' => 'a'
Expected Output : 'a'
Got Output : 'a'
ok 4 - 'aabccba' ->'a'
...

*** Input: abcddcba
Remove 'dd' => 'abccba'
Remove 'cc' => 'abba'
Remove 'bb' => 'aa'
Remove 'aa' => ''
Expected Output : ''
Got Output : ''
ok 5 - 'abcddcba' ->''
...

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