32804번 - Taking Out the Trash 다국어

문제

Peter has way too much trash and he needs to take it all out.

Specifically, there are $n$ bags of trash each with a specific weight. Peter can hold either one or two bags of trash per trip, and he can carry a maximum total of $m$ milligrams of trash in a single trip. What is the minimum number of trips Peter needs to take to take out all the trash?

입력

The input starts with two integers $n$ $(1 \le n \le 5 \cdot 10^5)$ and $m$ $(1 \le m \le 10^9),ドル the number of bags of trash and the maximum weight of trash Peter can carry.

The next line contains $n$ integers, $w_i$ $(1 \le w_i \le m),ドル the weight of each bag of trash in milligrams.

출력

Output the minimum number of trips Peter needs to make to take out all the trash.

제한

힌트