$$\underbrace{\widehat{\overline{\left|\stackrel{\ }{\ \cup}\stackrel{\bigcap^\cup}{}\stackrel{\ }{\cup^{\ }}\stackrel{\bigcap\cup}{}\right|}}}$$
源代码：
LaTeX
\underbrace{\widehat{\overline{\left|\stackrel{\ }{\ _\cup}\stackrel{\bigcap^\cup}{}\stackrel{\ }{\cup^{\ }}\stackrel{\bigcap_\cup}{}\right|}}}