A city would like to know how many vehicles it could move through its streets in an emergency. The most likely situation is an evacuation starting at the school and ending at the park. The connections between these two locations, plus their capacity and direction, is shown below.

The figure shows that during an emergency in a city, how many vehicles could move through the streets between a school and a park. Between the school and the Oak street $20$ vehicles could move. Between the Oak street and the first street $5$ vehicles could move. Between the first street and the park $10$ vehicles could move. Between the Oak street and the second street $20$ vehicles could move. Between the school and the Elm street $15$ vehicles could move. Between the Elm street and the second street $5$ vehicles could move. Between the second street and the park $5$ vehicles could move.

Path A B C D E F G

Capacity $30102010253030$

Maximum flow?