A pile of stones

题意翻译

有一堆石子，给一个长度为$n$的操作序列，"-"表示取出一个石子，"+"表示放入一个石子，求这堆石子最后至少有几个

题目描述

Vasya has a pile, that consists of some number of stones. $ n $ times he either took one stone from the pile or added one stone to the pile. The pile was non-empty before each operation of taking one stone from the pile. You are given $ n $ operations which Vasya has made. Find the minimal possible number of stones that can be in the pile after making these operations.

输入输出格式

输入格式

The first line contains one positive integer $ n $ — the number of operations, that have been made by Vasya ( $ 1 \leq n \leq 100 $ ). The next line contains the string $ s $ , consisting of $ n $ symbols, equal to "-" (without quotes) or "+" (without quotes). If Vasya took the stone on $ i $ -th operation, $ s_i $ is equal to "-" (without quotes), if added, $ s_i $ is equal to "+" (without quotes).

输出格式

Print one integer — the minimal possible number of stones that can be in the pile after these $ n $ operations.

输入输出样例

输入样例 #1

3
---

输出样例 #1

0

输入样例 #2

4
++++

输出样例 #2

4

输入样例 #3

2
-+

输出样例 #3

1

输入样例 #4

5
++-++

输出样例 #4

3

说明

In the first test, if Vasya had $ 3 $ stones in the pile at the beginning, after making operations the number of stones will be equal to $ 0 $ . It is impossible to have less number of piles, so the answer is $ 0 $ . Please notice, that the number of stones at the beginning can't be less, than $ 3 $ , because in this case, Vasya won't be able to take a stone on some operation (the pile will be empty). In the second test, if Vasya had $ 0 $ stones in the pile at the beginning, after making operations the number of stones will be equal to $ 4 $ . It is impossible to have less number of piles because after making $ 4 $ operations the number of stones in the pile increases on $ 4 $ stones. So, the answer is $ 4 $ . In the third test, if Vasya had $ 1 $ stone in the pile at the beginning, after making operations the number of stones will be equal to $ 1 $ . It can be proved, that it is impossible to have less number of stones after making the operations. In the fourth test, if Vasya had $ 0 $ stones in the pile at the beginning, after making operations the number of stones will be equal to $ 3 $ .