#include <cstdio>
#include <vector>

using namespace std;

const int N = (int) 1e5 + 7;
int n, far, dep[N];
vector<int> g[N];

void dfs(int a, int p = -1) {
  if (dep[a] > dep[far]) {
    far = a;
  }
  for (auto &b : g[a]) {
    if (b != p) {
      dep[b] = 1 + dep[a];
      dfs(b, a);
    }
  }
}

void fnd(int a) {
  dep[a] = 0;
  far = a;
  dfs(a);
}

int main() {
  freopen ("revolta.in", "r", stdin);
  freopen ("revolta.out", "w", stdout);

  int tests;
  scanf("%d", &tests);
  while (tests--) {
    int n;
    scanf("%d %d", &n);
    for (int i = 0; i < n; i++) {
      g[i].clear();
    }
    for (int i = 0; i < n - 1; i++) {
      int a, b;
      scanf("%d %d", &a, &b);
      g[a].push_back(b);
      g[b].push_back(a);
    }
    fnd(1);
    fnd(far);
    int val = dep[far], k = val / 3;
    val = 2 * k + val % 3;
    printf("%d\n", val);
  }
}