402349: GYM100735 D Triangle Formation

Memory Limit：64 MB Time Limit：0 S
Judge Style：Text Compare Creator：
Submit：0 Solved：0

Description

D. Triangle Formationtime limit per test0.25 secondsmemory limit per test64 megabytesinputstandard inputoutputstandard output

You are given N wooden sticks. Your task is to determine how many triangles can be made from the given sticks without breaking them. Each stick can be used in at most one triangle.

Input

The first line of each test case contains the number of sticks N. (1 ≤ N ≤ 15)

The second line of each test case contains N integers leni that are the lengths of the sticks. (1 ≤ leni ≤ 109).

Output

Output single integer R – the maximal number of triangles.

ExamplesInput
2
1 1
Output
0
Input
3
2 2 2
Output
1
Input
6
2 2 3 4 5 6
Output
2

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