1 #include<cstdio>
 2 const int M=200005;
 3 int ed,cnt,fa[M],q[M],dep[M],v[M<<1],nex[M<<1],hea[M];
 4 bool vis[M];
 5 
 6 int read()
 7 {
 8     int x=0; char ch=getchar();
 9     while (ch<‘0‘ || ch>‘9‘) ch=getchar();
10     while (ch>=‘0‘ && ch<=‘9‘) x=(x<<1)+(x<<3)+ch-48,ch=getchar();
11     return x;
12 }
13 
14 void add(int x,int y) { v[++cnt]=y,nex[cnt]=hea[x],hea[x]=cnt; }
15 
16 void build(int s)
17 {
18     int h=0,t=1; fa[s]=0;
19     dep[q[1]=ed=s]=1;
20     while (h^t)
21     {
22         int x=q[++h],y,i;
23         for (i=hea[x];i;i=nex[i])
24             if (!vis[y=v[i]] && y^fa[x])
25             {
26                 dep[y]=dep[fa[q[++t]=y]=x]+1;
27                 if (dep[ed]<dep[y]) ed=y;
28             }
29     }
30 }
31 
32 void getdis(int x) { build(x); build(ed); }
33 
34 int main()
35 {
36     for (int T=read();T;--T)
37     {
38         int n=read(),ans,i,len,x,y,z;
39         for (cnt=i=0;i<=n;++i) hea[i]=0;
40         for (i=1;i<n;++i)
41         {
42             x=read(),y=read();
43             add(x,y),add(y,x);
44         }
45         getdis(1); len=dep[x=ed];
46         for (;dep[x]!=(len>>1)+1;x=fa[x]);
47         vis[x]=1; getdis(fa[x]); len=dep[y=ed];
48         for (;dep[y]!=(len>>1)+1;y=fa[y]);
49         ans=len>>1; vis[x]=0; vis[z=fa[x]]=1;
50         getdis(x); len=dep[ed]; vis[z]=0;
51         for (;dep[ed]!=(len>>1)+1;ed=fa[ed]);
52         len=len>>1; if (ans<len) ans=len;
53         printf("%d %d %d\n",ans,y,ed);
54     }
55     return 0;
56 }