file1 contents:  1. Ram/is/going/reg[30]  2. he/is/coming/reg[31]  3. what/goes/on/reg[32]
 file2 contents:  1. is/coming/reg[31]     2. on/reg[32]     3. try/to/do/reg[65]
 output file contents:  Ram/is/going/reg[30]