#include <bits/stdc++.h>
using namespace std;
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n;
    cin >> n;
    string s;
    cin >> s;
    int flag = 1;
    int st;
    char c = s[0];
    for (int i = 1; i < n; i++) {
      if (s[i] == c)
        continue;
      else {
        st = i;
        flag = 0;
        break;
      }
    }
    if (flag == 1) {
      cout << (n + 2) / 3 << endl;
      continue;
    }
    int ans = 0;
    int m = 1;
    c = s[st];
    int val = (st + 1) % n;
    for (int i = val; i != st; i = ((i + 1) % n)) {
      if (s[i] == c) {
        m++;
      } else {
        if (m >= 3) ans += (m) / 3;
        c = s[i];
        m = 1;
      }
    }
    if (m >= 3) ans += (m / 3);
    cout << ans << endl;
  }
  return 0;
}
