#include <cstdio>#include <cstring>#include <algorithm>#include <queue>#include <stack>#include <map>#include <set>#include <climits>#include <iostream>#include <string>using namespace std; #define MP make_pair#define PB push_backtypedef long long LL;typedef unsigned long long ULL;typedef vector<int> VI;typedef pair<int, int> PII;typedef pair<double, double> PDD;const int INF = INT_MAX / 3;const double eps = 1e-8;const LL LINF = 1e17;const double DINF = 1e60;const int maxn = 2e5 + 10;int head[maxn], nxt[maxn << 1], u[maxn << 1], v[maxn << 1], ecnt;int n, dist[maxn], pre[maxn], path[maxn], id[maxn];bool vis[maxn], del[maxn << 1];void adde(int uu, int vv) {    u[ecnt] = uu; v[ecnt] = vv; nxt[ecnt] = head[uu]; head[uu] = ecnt++;}//bfs 参数为起点， 返回终点（离起点最远的一个点）int bfs(int str, int col) {    memset(vis, 0, sizeof(vis));    vis[str] = true;    dist[str] = 0; pre[str] = -1;    queue<int> q; q.push(str);    int now = 0;    while(!q.empty()) {        now = q.front(); q.pop();        id[now] = col;        for(int i = head[now]; ~i; i = nxt[i]) if(!del[i]) {            if(!vis[v[i]]) {                pre[v[i]] = now;                dist[v[i]] = dist[now] + 1;                q.push(v[i]); vis[v[i]] = true;            }        }    }    return now;}void solve() {    //第一遍， 求树的直径    int s, t, len = 0, du, dv;    s = bfs(1, -1); t = bfs(s, -1);    for(int i = t; ~i; i = pre[i]) {        path[len++] = i;    }    //删除最中间的边    for(int i = t, j = 0; ~i; i = pre[i], j++) {        if((j + 1) == len / 2) {            du = i; dv = pre[i]; break;        }    }    for(int i = 0; i < ecnt; i++) {        if((u[i] == du && v[i] == dv) || (u[i] == dv && v[i] == du)) {            del[i] = true;        }    }    //对两边的子树分别求直径    int maxlen = 0, p[2], pcnt = 0;    for(int i = 1; i <= n; i++) if(id[i] == -1) {        s = bfs(i, pcnt); t = bfs(s, pcnt);        len = 0;        for(int j = t; ~j; j = pre[j]) path[len++] = j;        for(int j = t, k = 0; ~j; j = pre[j], k++) if((k + 1) == (len + 1) / 2) {            p[pcnt++] = j; break;        }        maxlen = max(maxlen, len / 2);    }    printf("%d %d %d\n", maxlen, p[0], p[1]);}int main() {    int T; scanf("%d", &T);    while(T--) {        ecnt = 0;        scanf("%d", &n);        memset(head, -1, sizeof(head));        memset(del, 0, sizeof(del));        for(int i = 0; i < n - 1; i++) {            int a, b; scanf("%d%d", &a, &b);            adde(a, b); adde(b, a);        }        solve();    }    return 0;}