[{"sectionTitle":"题目描述","type":"Text","text":"Hecy 又接了个新任务：BE 处理。BE 中有一类被称为 GBE。\r\n\r\n以下是 GBE 的定义：\r\n1. 空表达式是 GBE\r\n2. 如果表达式 A 是 GBE，则 [A] 与 (A) 都是 GBE\r\n3. 如果 A 与 B 都是 GBE，那么 AB 是 GBE\r\n\r\n下面给出一个 BE，求至少添加多少字符能使这个 BE 成为 GBE。","subType":"markdown"},{"sectionTitle":"输入格式","type":"Text","text":"输入仅一行，为字符串 BE。","subType":"markdown"},{"sectionTitle":"输出格式","type":"Text","text":"输出仅一个整数，表示增加的最少字符数。","subType":"markdown"},{"sectionTitle":"样例","type":"Sample","text":"","subType":"markdown","payload":["[])","1"]},{"sectionTitle":"数据范围与提示","type":"Text","text":"对于 $100\\%$ 的数据，输入的字符串长度小于 $100$。","subType":"markdown"}]