CF624B.Making a String

You are given an alphabet consisting of n letters, your task is to make a string of the maximum possible length so that the following conditions are satisfied:

• the i-th letter occurs in the string no more than a__i times;
• the number of occurrences of each letter in the string must be distinct for all the letters that occurred in the string at least once.

给你一个由 $n$ 个字母组成的字母表，你的任务是构造一个尽可能长的字符串，使得以下条件均满足：

• 第 $i$ 个字母在字符串中出现的次数不超过 $a_i$ 次；
• 字符串中每个至少出现一次的字母的出现次数必须互不相同。

The first line of the input contains a single integer n (2  ≤  n  ≤  26) — the number of letters in the alphabet.

The next line contains n integers a__i (1 ≤ a__i ≤ 109) — i-th of these integers gives the limitation on the number of occurrences of the i-th character in the string.

输入的第一行包含一个整数 $n$（$2 \leq n \leq 26$）—— 表示字母表中的字母个数。

接下来的一行包含 $n$ 个整数 $a_i$（$1 \leq a_i \leq 10^9$）—— 其中第 $i$ 个整数表示字符串中第 $i$ 个字符的出现次数限制。

Print a single integer — the maximum length of the string that meets all the requirements.

输出一个整数——满足所有要求的字符串的最大长度。

For convenience let's consider an alphabet consisting of three letters: "a", "b", "c". In the first sample, some of the optimal strings are: "cccaabbccbb", "aabcbcbcbcb". In the second sample some of the optimal strings are: "acc", "cbc".

为方便起见，我们考虑一个由三个字母组成的字母表：“a”、“b”、“c”。在第一个样例中，一些最优字符串包括：“cccaabbccbb”、“aabcbcbcbcb”。在第二个样例中，一些最优字符串包括：“acc”、“cbc”。