Step-second position status used
1. Xiaoming and Xiaoming's brother go first. 0+3=3 seconds AB-CDE
Xiaoming's brother is back. 3+3=6 seconds BCDE
Xiaoming's mother and grandfather went there. 6+ 12= 18 sec ADE-BC
Xiao Ming is back. 18+ 1= 19 seconds to go to ABC.
Xiaoming and his father went there. 19+6=25 seconds
6. Xiaoming is back. 25+ 1=26 seconds CDE-AB
Xiao Ming and his brother went there. 26+3=29 seconds abcde-it's all over.