CF245E.Mishap in Club

Polycarpus just has been out of luck lately! As soon as he found a job in the "Binary Cat" cafe, the club got burgled. All ice-cream was stolen.

On the burglary night Polycarpus kept a careful record of all club visitors. Each time a visitor entered the club, Polycarpus put down character "+" in his notes. Similarly, each time a visitor left the club, Polycarpus put character "-" in his notes. We know that all cases of going in and out happened consecutively, that is, no two events happened at the same time. Polycarpus doesn't remember whether there was somebody in the club at the moment when his shift begun and at the moment when it ended.

Right now the police wonders what minimum number of distinct people Polycarpus could have seen. Assume that he sees anybody coming in or out of the club. Each person could have come in or out an arbitrary number of times.

波利卡普斯最近运气一直不好！他刚在“二进制猫”咖啡馆找到一份工作，俱乐部就遭到了盗窃——所有冰淇淋都被偷走了。

在盗窃发生的当晚，波利卡普斯仔细记录了所有到访俱乐部的客人。每当有客人进入俱乐部，波利卡普斯就在笔记中记下一个字符 +；类似地，每当有客人离开俱乐部，他就记下字符 -。我们知道，所有进出事件都是依次发生的，即没有任何两个事件在同一时刻发生。波利卡普斯不记得自己值班开始和结束的时刻，俱乐部里是否已有客人。

目前警方想知道：波利卡普斯所见到的不同人数的最小可能值是多少？假设他能看见任何进出俱乐部的人。每个人可以任意多次进出俱乐部。

The only line of the input contains a sequence of characters "+" and "-", the characters are written one after another without any separators. The characters are written in the order, in which the corresponding events occurred. The given sequence has length from 1 to 300 characters, inclusive.

输入仅有一行，包含一串由“+”和“-”组成的字符，这些字符连续书写，中间没有任何分隔符。字符的书写顺序与对应事件的发生顺序一致。给定序列的长度为 $1$ 到 $300$（含端点）。

Print the sought minimum number of people

输出所求的最少人数