题目描述
Snuke loves puzzles.
Today, he is working on a puzzle using S- and c-shaped pieces.
In this puzzle, you can combine two c-shaped pieces into one S-shaped piece, as shown in the figure below:
Snuke decided to create as many Scc groups as possible by putting together one S-shaped piece and two c-shaped pieces.
Find the maximum number of Scc groups that can be created when Snuke has N S-shaped pieces and M c-shaped pieces.
-----Constraints-----
- 1 ≤ N,M ≤ 10^{12}
-----Input-----
The input is given from Standard Input in the following format:
N M
-----Output-----
Print the answer.
-----Sample Input-----
1 6
-----Sample Output-----
2
Two Scc groups can be created as follows:
- Combine two c-shaped pieces into one S-shaped piece
- Create two Scc groups, each from one S-shaped piece and two c-shaped pieces
输入格式
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输出格式
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