#include <cstdio>
#include <vector>
#include <cstring>
#define N 100002

using namespace std;
vector<int>v[N];
int x, y, n, i, last, viz[N], D;

void dfs_1(int nod, int niv)
{
    viz[nod] = 1;
    for(vector<int>::iterator it=v[nod].begin(); it!=v[nod].end(); it++)
        if(!viz[*it])
            dfs_1(*it, niv+1);
    if(niv > D)
    {
        D = niv;
        last = nod;
    }
}

void dfs_2(int nod, int niv)
{
    viz[nod] = 0;
    for(vector<int>::iterator it=v[nod].begin(); it!=v[nod].end(); it++)
        if(viz[*it])
            dfs_2(*it, niv+1);
    if(niv > D)
        D = niv;
}

int main()
{
    freopen("revolta.in", "r", stdin);
    freopen("revolta.out", "w", stdout);
    int T;
    scanf("%d", &T);
    while(T--)
    {
        scanf("%d",&n);
        D = 0;
        last = 0;
        for(int i=0; i<=n; ++i)
            v[i].clear();
        memset(viz, 0, sizeof(viz));

        for(i=1; i<=n-1; i++)
        {
            scanf("%d %d",&x, &y);
            v[x].push_back(y);
            v[y].push_back(x);
        }
        dfs_1(1, 1);
        dfs_2(last, 1);
        printf("%d\n", (D+1)/2);
    }
    return 0;
}