#include <bits/stdc++.h>
using namespace std;
long long int max(long long int a, long long int b) {
  if (a > b) {
    return a;
  }
  return b;
}
long long int gcd(long long int a, long long int b) {
  if (a == 0) {
    return b;
  }
  return gcd(b % a, a);
}
long long int min(long long int a, long long int b) {
  if (a < b) {
    return a;
  }
  return b;
}
long long int power(long long int x, long long int n) {
  long long int res = 1;
  while (n > 0) {
    if (n % 2 == 1) {
      res = (res * x);
    }
    x = (x * x);
    n = n / 2;
  }
  return res;
}
long long int factorialNumInverse[1000001];
long long int naturalNumInverse[1000001];
long long int fact[1000001];
void InverseofNumber(long long int n, long long int p) {
  naturalNumInverse[0] = naturalNumInverse[1] = 1;
  for (long long int i = 2; i <= n; i++)
    naturalNumInverse[i] = naturalNumInverse[p % i] * (p - p / i) % p;
}
void InverseofFactorial(long long int n, long long int p) {
  factorialNumInverse[0] = factorialNumInverse[1] = 1;
  for (long long int i = 2; i <= n; i++)
    factorialNumInverse[i] =
        (naturalNumInverse[i] * factorialNumInverse[i - 1]) % p;
}
void factorial(long long int n, long long int p) {
  fact[0] = 1;
  for (long long int i = 1; i <= n; i++) {
    fact[i] = (fact[i - 1] * i) % p;
  }
}
long long int nCrModp(long long int n, long long int r, long long int p) {
  long long int ans =
      ((fact[n] * factorialNumInverse[r]) % p * factorialNumInverse[n - r]) % p;
  return ans;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long int tc;
  cin >> tc;
  factorial(200005, 1000000007);
  InverseofNumber(200005, 1000000007);
  InverseofFactorial(200005, 1000000007);
  while (tc--) {
    long long int n;
    cin >> n;
    string s;
    cin >> s;
    long long int ans = 0;
    long long int i = 1;
    long long int len = 1;
    while (i < n) {
      if (s[i] == s[0]) {
        len++;
      }
      i++;
    }
    if (len == n) {
      cout << ceil((long double)n / (long double)3) << "\n";
      continue;
    }
    len = 0;
    i = 0;
    int j = s.length() - 1;
    while (j >= 0 && s[j] == s[0]) {
      len++;
      j--;
    }
    while (i <= j && s[i] == s[0]) {
      len++;
      i++;
    }
    ans += (len) / 3;
    len = 1;
    i++;
    while (i <= j) {
      if (s[i] == s[i - 1]) {
        len++;
      } else {
        ans += (len) / 3;
        len = 1;
      }
      i++;
    }
    ans += (len) / 3;
    cout << ans << "\n";
  }
  return 0;
}
