How do you win Family crisis logic puzzle ?

You play the game Family Crisis? A very good logic games. if you have not played.

Now! Please explore and experience this game logic at frivschool! 

How do you win Family crisis logic puzzle ?

If you need instructions please follow these steps:

1) One and two cross the lake, two returns => four seconds

2) Four and five cross the lake, one return. => nineteen seconds

3) One and three cross the lake, one return =>twenty-six seconds

4) One and two cross the lake => twenty-nine seconds

==> Win