#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

typedef tree<
pair<int, int>,
null_type,
less<pair<int, int>>,
rb_tree_tag,
tree_order_statistics_node_update> ordered_set;

const int maxn = 2e5;

vector<pair<int, int>> g[maxn];
vector<int> que[maxn];
ordered_set e[maxn];
int knum[maxn];
int ans[maxn];

void dfs(int v = 1, int p = 0)
{
	for(auto it: g[v])
	{
		int u = it.first;
		int c = it.second;
		if(u == p)
			continue;
		e[v].insert({c, u});
		dfs(u, v);
		if(e[v].size() < e[u].size())
			e[v].swap(e[u]);
		for(auto it: e[u])
			e[v].insert(it);
	}
	for(auto it: que[v])
	{
		if(knum[it] > e[v].size())
			ans[it] = 1e9;
		else
			ans[it] = e[v].find_by_order(knum[it] - 1) -> first;
	}
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int n, q;
	cin >> n >> q;
	for(int i = 0; i < n - 1; i++)
	{
		int a, b, c;
		cin >> a >> b >> c;
		g[a].push_back({b, c});
		g[b].push_back({a, c});
	}
	for(int i = 1; i <= q; i++)
	{
		int u, k;
		cin >> u >> k;
		knum[i] = k;
		que[u].push_back(i);
	}
	dfs();
	for(int i = 1; i <= q; i++)
	{
		if(ans[i] == 1e9)
			cout << "nan";
		else
			cout << ans[i];
		cout << "\n";
	}
	return 0;
}