Puzzle - Jungle crossing

[Naresh]

1st round----1 and 3 will go and 1 will come back

1,6,8,12======3
total time=3+1=4 minutes

2nd round----8and 12 will go and 3 will come back
1,3,6====8,12
total time---4+12+3=19 minutes

3rd round --- 1 and 6 will go and 1 will come back
1,3====6,8,12
total time----19+6+1=26 minutes

4th round..1 and 3 will go and all will be right there
no one====1,3,6,8,12
total time---26+3=29 minutes

Hoping I am right.

[Naynish]

29 sec
combinations: 1,3
12,8
6,1
1,3