detect, the double, frontal or rear, according to the 6 letters .

detect, the double, frontal or rear, according to the 6 letters
in the 6 letters we have 6 conditions of pairs, sometimes we have double in two, letters, mark the two letters
* The binary = is to find the front and back pair
https://www.excelforum.com/attachmen...1&d=1546084749