#include<cstdio>
#include<vector>
#include<algorithm>
#include<queue>
using namespace std;
vector<int>L[100100];
int t,n,i,j,a,b,v[100100],d[100100];
FILE *f,*g;
int maxim(int a,int b){
    if(a>b)
        return a;
    return b;
}
int cmp(int a,int b){
    return d[a]>d[b];
}
void dfs(int nod){
    priority_queue<int>h;
    d[nod]=0;
    v[nod]=1;
    for(int i=0;i<L[nod].size();i++){
        if( v[ L[nod][i] ] == 0 ){
            dfs(L[nod][i]);
            h.push( d[ L[nod][i] ] );
        }
    }
    i=1;
    while(h.size()){
        d[nod] = maxim( d[nod] , h.top() + i );
        h.pop();
        i++;
    }
}
int main(){
    f=fopen("zvon.in","r");
    g=fopen("zvon.out","w");
    fscanf(f,"%d",&t);
    while(t--){
        fscanf(f,"%d",&n);
        for(i=1;i<=n;i++){
            L[i].clear();
            v[i]=0;
        }
        for(i=1;i<n;i++){
            fscanf(f,"%d%d",&a,&b);
            L[a].push_back(b);
        }
        dfs(1);
        fprintf(g,"%d\n",d[1]);
    }
    fclose(f);
    fclose(g);
    return 0;
}