Counting points

The jury of the Potyczki Algorytmiczne is tired of counting points for every submission. Write a program that automates this process.

Each problem awards between 0 and 10 points. A problem has $n$ tests, where $n$ is divisible by 10. A solution earns 1 point if it solves all of the first $n/10$ tests. It earns another point if it solves all of the next $n/10$ tests. Each group of $n/10$ tests can earn its point independently, but only if every test in that group is solved correctly. A single mistake in a group means that group earns no point.

Note: To keep things simple, we assume every test group has the same number of tests. In a real contest, this may not be true.

Note 2: Any code you write may be used against you.*

• A cosmonaut joke.

The first line contains an integer $n$ ($10 \le n \le 100$, $n$ is divisible by 10), the number of tests.

The second line contains a string of $n$ characters, each either 'T' or 'N'. 'T' means the test was solved correctly. 'N' means it was not.

Print one integer, the number of points earned.

Explanation of the first example: The solution earns one point each for groups 1, 3, and 10. Groups 4 and 5 are partially solved, so they earn no points.