CF1203E.Boxers

There are $n$ boxers, the weight of the $i$-th boxer is $a_i$. Each of them can change the weight by no more than $1$ before the competition (the weight cannot become equal to zero, that is, it must remain positive). Weight is always an integer number.

It is necessary to choose the largest boxing team in terms of the number of people, that all the boxers' weights in the team are different (i.e. unique).

Write a program that for given current values $a_i$ will find the maximum possible number of boxers in a team.

It is possible that after some change the weight of some boxer is $150001$ (but no more).

有 $n$ 名拳击手，第 $i$ 名拳击手的体重为 $a_i$。每名拳击手在比赛前最多可将自身体重改变 $1$（体重不能变为零，即必须保持为正整数）。体重始终为整数。

需要选出人数最多的拳击队，使得队中所有拳击手的体重互不相同（即体重唯一）。

请编写一个程序，对于给定的当前体重值 $a_i$，求出所能组成的最大人数的拳击队。

注意：某些拳击手在调整体重后，其体重可能达到 $150001$（但不会超过该值）。

The first line contains an integer $n$ ($1 \le n \le 150000$) — the number of boxers. The next line contains $n$ integers $a_1, a_2, \dots, a_n$, where $a_i$ ($1 \le a_i \le 150000$) is the weight of the $i$-th boxer.

第一行包含一个整数 $n$（$1 \le n \le 150000$）——拳击手的数量。
下一行包含 $n$ 个整数 $a_1, a_2, \dots, a_n$，其中 $a_i$（$1 \le a_i \le 150000$）表示第 $i$ 个拳击手的体重。

Print a single integer — the maximum possible number of people in a team.

输出一个整数——团队中可能的最大人数。

In the first example, boxers should not change their weights — you can just make a team out of all of them.

In the second example, one boxer with a weight of $1$ can be increased by one (get the weight of $2$), one boxer with a weight of $4$ can be reduced by one, and the other can be increased by one (resulting the boxers with a weight of $3$ and $5$, respectively). Thus, you can get a team consisting of boxers with weights of $5, 4, 3, 2, 1$.

在第一个例子中，拳击手的体重不应发生变化——您可以直接由所有拳击手组成一支队伍。

在第二个例子中，一名体重为 $1$ 的拳击手可增加 $1$（体重变为 $2$），一名体重为 $4$ 的拳击手可减少 $1$，另一名体重为 $4$ 的拳击手可增加 $1$（最终体重分别为 $3$ 和 $5$）。因此，您可以得到一支由体重为 $5, 4, 3, 2, 1$ 的拳击手组成的队伍。