#include <bits/stdc++.h>
using namespace std;
const int INF = 1 << 30;
const long long int MAX = 1e9 + 7;
void array_show(int *array, int array_n, char middle = ' ') {
  for (int i = 0; i < array_n; i++)
    printf("%d%c", array[i], (i != array_n - 1 ? middle : '\n'));
}
void array_show(long long int *array, int array_n, char middle = ' ') {
  for (int i = 0; i < array_n; i++)
    printf("%lld%c", array[i], (i != array_n - 1 ? middle : '\n'));
}
void array_show(vector<int> &vec_s, int vec_n = -1, char middle = ' ') {
  if (vec_n == -1) vec_n = vec_s.size();
  for (int i = 0; i < vec_n; i++)
    printf("%d%c", vec_s[i], (i != vec_n - 1 ? middle : '\n'));
}
void array_show(vector<long long int> &vec_s, int vec_n = -1,
                char middle = ' ') {
  if (vec_n == -1) vec_n = vec_s.size();
  for (int i = 0; i < vec_n; i++)
    printf("%lld%c", vec_s[i], (i != vec_n - 1 ? middle : '\n'));
}
void init() {}
void solve() {
  int n, m;
  int i, j, k;
  int a, b, c;
  string sa;
  vector<int> v1;
  cin >> n;
  cin >> sa;
  a = 1;
  for (i = 0; i < n - 1; i++) {
    if (sa[i] != sa[i + 1]) {
      v1.push_back(a);
      a = 1;
    } else
      a++;
  }
  if (v1.empty()) {
    cout << (n - 1) / 3 + 1 << endl;
    return;
  }
  if (sa[0] != sa.back())
    v1.push_back(a);
  else
    v1[0] += a;
  b = 0;
  for (i = 0; i < v1.size(); i++) {
    b += v1[i] / 3;
  }
  cout << b << endl;
}
int main() {
  int n, i;
  init();
  cin >> n;
  for (i = 0; i < n; i++) {
    solve();
  }
}
