Micromasters Certificates

The Department of Computer Engineering has provided several micromasters, each with a curriculum. A student who completes all the courses of a micromaster receives that micromaster's certificate. A course may appear in the curriculum of several micromasters. Soroush only cares about earning a certificate, not which type it is. He wants to earn $3$ micromaster certificates while taking the minimum possible number of courses. The curriculums are posted on a bulletin board. Help Soroush reach his goal using these curriculums.

The input is a bulletin board of at most $400$ rows and $400$ columns. Each micromaster curriculum is enclosed in a rectangular box. The board border and the curriculum boxes are drawn with + for corners, - for horizontal sides, and | for vertical sides. The curriculum boxes do not share any characters, and each box has its own border. Each line inside a box contains at most one course name. Course names consist of letters, digits, and spaces. Course names are not case-sensitive, and spaces are ignored. For example, General math1 and generalMath 1 are the same course. There are at most $50$ curriculum boxes, and each box contains at most $30$ courses. The board has at least $3$ boxes, and each box contains at least $1$ course.

Print a single line containing the minimum number of courses Soroush must take to earn at least $3$ certificates.