#include <bits/stdc++.h>
using namespace std;
char str[200005];
int main() {
  int ts;
  scanf("%d", &ts);
  while (ts--) {
    int n;
    scanf("%d %s", &n, str);
    vector<int> vec;
    for (int i = 0; i < n; i++) {
      int j = i, c = 0;
      while (i < n && str[i] == str[j]) i++, c++;
      i--;
      vec.push_back(c);
    }
    if (vec.size() == 1 && vec[0] > 2) vec[0] += 2;
    if (vec.size() != 1 && str[0] == str[n - 1])
      vec[0] += vec.back(), vec.pop_back();
    int res = 0;
    for (int i = 0; i < vec.size(); i++) res += vec[i] / 3;
    printf("%d\n", res);
  }
  return 0;
}
