CF962D.Merge Equals

You are given an array of positive integers. While there are at least two equal elements, we will perform the following operation. We choose the smallest value $x$ that occurs in the array $2$ or more times. Take the first two occurrences of $x$ in this array (the two leftmost occurrences). Remove the left of these two occurrences, and the right one is replaced by the sum of this two values (that is, $2 \cdot x$).

Determine how the array will look after described operations are performed.

For example, consider the given array looks like $[3, 4, 1, 2, 2, 1, 1]$. It will be changed in the following way: $[3, 4, 1, 2, 2, 1, 1]~\rightarrow~[3, 4, 2, 2, 2, 1]~\rightarrow~[3, 4, 4, 2, 1]~\rightarrow~[3, 8, 2, 1]$.

If the given array is look like $[1, 1, 3, 1, 1]$ it will be changed in the following way: $[1, 1, 3, 1, 1]~\rightarrow~[2, 3, 1, 1]~\rightarrow~[2, 3, 2]~\rightarrow~[3, 4]$.

给你一个正整数数组。只要数组中至少存在两个相等的元素，我们就执行如下操作：选择数组中出现次数不少于 $2$ 次的最小值 $x$；找出该值 $x$ 在数组中最左侧的两个出现位置（即最靠左的两个）；删除其中左侧的那个，将右侧那个替换为这两个值之和（即 $2 \cdot x$）。

请确定执行完上述所有操作后，数组最终的形态。

例如，若初始数组为 $[3, 4, 1, 2, 2, 1, 1]$，则变化过程如下：
$[3, 4, 1, 2, 2, 1, 1]~\rightarrow~[3, 4, 2, 2, 2, 1]~\rightarrow~[3, 4, 4, 2, 1]~\rightarrow~[3, 8, 2, 1]$。

若初始数组为 $[1, 1, 3, 1, 1]$，则变化过程如下：
$[1, 1, 3, 1, 1]~\rightarrow~[2, 3, 1, 1]~\rightarrow~[2, 3, 2]~\rightarrow~[3, 4]$。

The first line contains a single integer $n$ ($2 \le n \le 150\,000$) — the number of elements in the array.

The second line contains a sequence from $n$ elements $a_1, a_2, \dots, a_n$ ($1 \le a_i \le 10^{9}$) — the elements of the array.

第一行包含一个整数 $n$（$2 \le n \le 150\,000$）—— 表示数组中元素的个数。

第二行包含一个由 $n$ 个元素组成的序列 $a_1, a_2, \dots, a_n$（$1 \le a_i \le 10^{9}$）—— 表示数组的元素。

In the first line print an integer $k$ — the number of elements in the array after all the performed operations. In the second line print $k$ integers — the elements of the array after all the performed operations.

第一行输出一个整数 $k$ —— 所有操作完成后数组中的元素个数。
第二行输出 $k$ 个整数 —— 所有操作完成后数组的元素。

The first two examples were considered in the statement.

In the third example all integers in the given array are distinct, so it will not change.

前两个示例已在题目描述中给出。

在第三个示例中，给定数组中的所有整数互不相同，因此数组不会发生变化。