Longest Run of X's

Gru and Lucy are breaking into El Macho's lair. In front of them is a hallway that may be booby-trapped. The hallway is a single row of squares, and every square is marked either X or O. Gru believes that only the squares in the longest run of consecutive X marks are safe.

For each hallway, count how many squares are safe.

The first line contains the number of test cases $T$. $T$ is less than 100.

Each of the following lines holds one test case. The first number on the line is the number of squares $n$, followed by $n$ strings separated by spaces. Each string is either X or O.

$n$ is at least 1, and the sum of $n$ over all test cases is at most 200000.

For each test case, find the length $L$ of the longest run of consecutive X marks and print one line in this format.

The longest contiguous subsequence of X's is of length L

Write $L$ as a plain integer. If the hallway has no X at all, $L$ is 0.