Codeforces Heuristic Contest 001

From Codeforces. Geometry. Solve the geometry problem "Codeforces Heuristic Contest 001".

Examples
Input: [1,2,3]
Output: 0
Hints

Codeforces Heuristic Contest 001

**From Codeforces.** Geometry. Solve the geometry problem "Codeforces Heuristic Contest 001".