SPOJ POTHOLE

203 (POTHOLE) - Potholers

 * https://www.spoj.pl/problems/POTHOLE/

Summary
A text book max flow exercise.

Explanation
No explanation needed.

Input
1 12 4 3 4 2 5 1 8 2 9 7 2 6 11 1 8 2 9 10 2 10 11 1 12 2 10 12 1 12 1 12

Output
3