#include <fstream>
#include <iostream>
#include <vector>
#include <queue>
#include <utility>
#include <cstring>
#include <algorithm>

using namespace std;
vector<int> angs[100010];
int angajati;

bool compar(int a, int b) { 
	return angs[b].size() < angs[a].size();
}

int main(int argc, char** argv) {
	ifstream fi("zvon.in");
	ofstream fo("zvon.out");

	int teste;
	int angajati;

	fi >> teste;
	for (int i = 0; i < teste; ++i) {
		fi >> angajati;
		if (angajati > 1) {
			int x, y;
			memset(angs, 0, sizeof(angs));
			for (int j = 0; j < angajati - 1; ++j) {
				fi >> x >> y;
				angs[x - 1].push_back(y - 1);
			}
			queue< pair<int, int> > order;
			for (int j = 0; j < angajati; j++) {
				if (angs[j].size() >  1)
					sort(angs[j].begin(), angs[j].end(), compar);
				// cout <<j <<" : ";
				// for (size_t k = 0; k < angs[j].size(); k++) {
				// 	cout << angs[j][k] << "   ";
				// }
				// cout << "\n";
			}

			order.push(make_pair(0, 0));
			int mm = 0;
			while (1) {
				pair<int, int> x = order.front();
				order.pop();
				if (x.second > mm)
					mm = x.second;
				
				for (unsigned int vec = 0; vec < angs[x.first].size(); vec++)
					order.push(make_pair(angs[x.first][vec], x.second + 1 + vec));
			
				if (order.empty()) {
					fo << mm << "\n";
					break;
				} 
			}
		} else {
			fo << "0\n" << flush;
		}

	}
	return 0;
}