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**Task** | Statistics

Time limit: | 1.00 s | Memory limit: | 512 MB |

There are $n$ children who want to go to a Ferris wheel, and your task is to find a gondola for each child.

Each gondola may have one or two children, and in addition, the total weight in one gondola can be at most $x$. You know the weight of every child.

What is the minimum number of gondolas needed for the children?

The first input line contains two integers $n$ and $x$: the number of children and the maximum allowed weight.

The next line contains $n$ integers $p_1,p_2,\ldots,p_n$: the weight of each child.

Print one integer: the minimum number of gondolas.

- $1 \le n \le 5 \cdot 10^5$

- $1 \le x \le 10^9$

- $1 \le p_i \le x$

Input:

`4 10`

7 2 3 9

Output:

`3`