#include <bits/stdc++.h>
using namespace std;
int get_index(int i, int j, int k) { return i * 4 + j * 2 + k; }
int diff(int i, int j) { return i != j; }
pair<int, string> input() {
  int n;
  cin >> n;
  string s;
  cin >> s;
  return make_pair(n, s);
}
int work2(int n, string s) {
  int first_diff = 1;
  for (; first_diff < n; first_diff++) {
    if (s[first_diff - 1] != s[first_diff]) break;
  }
  if (first_diff == n) return (n + 2) / 3;
  s = s.substr(first_diff, n - first_diff) + s.substr(0, first_diff);
  int start = 0;
  int ans = 0;
  for (int i = 1; i < n; i++) {
    if (s[i] != s[i - 1]) {
      ans += (i - start) / 3;
      start = i;
    }
  }
  ans += (n - start) / 3;
  return ans;
}
void work() {
  pair<int, string> in = input();
  int n = in.first;
  string s = in.second;
  cout << work2(n, s) << endl;
}
int main() {
  int t;
  cin >> t;
  while (t--) {
    work();
  }
  return 0;
}
