Polyphase mergeort the following list.

A W X B T R O P S G C

File 1: A W X R G

File 2: B T O P S C

File 3: A B T W X C G

File 4: O P R S

File 5: A B O P R S T W X

File 6: C G

Final file: A B C G O P R S T W X