#include <bits/stdc++.h>
using namespace std;
int main() {
  int t;
  cin >> t;
  while (t--) {
    int n, i;
    cin >> n;
    string s;
    int ans = 0;
    cin >> s;
    for (i = 1; i < n; i++) {
      if (s[i] != s[0]) break;
    }
    if (i != n) {
      int c = 1;
      for (int j = i + 1; j != i; j = (j + 1) % n) {
        if ((j != 0 && s[j] == s[j - 1]) || (j == 0 && s[0] == s[n - 1])) {
          c++;
        } else {
          while (c >= 3) {
            ans++;
            c -= 3;
          }
          c = 1;
        }
      }
      while (c >= 3) {
        ans++;
        c -= 3;
      }
    } else {
      int c = n - 1;
      ans = 1;
      while (c >= 3) {
        ans++;
        c -= 3;
      }
    }
    cout << ans << endl;
  }
}
