#include <bits/stdc++.h>
using namespace std;

#define int long long

const int N = 1005, M = 200005, inf = 2e18;
int n, q, a[N], head[N], tot, u, v, w, dis[N], ans;
bool vis[N], flag, flag_flower = 1;
vector<int> g;
map<pair<int, int>, int> mp;

struct edge {int to, nxt, val;} e[N << 1];

void add_edge(int u, int v, int w)
{
	e[++tot] = {v, head[u], w}, head[u] = tot;
}

void dfs(int x)
{
	if(flag) return;
	if(x == v)
	{
		flag = 1;
		for(auto h : g) ans = min(ans, max(a[h], dis[h]));
		return;
	}
	for(int i = head[x]; i; i = e[i].nxt)
	{
		if(!vis[e[i].to])
		{
			int tt = dis[e[i].to];
			vis[e[i].to] = 1, dis[e[i].to] = dis[x] + e[i].val, g.push_back(e[i].to);
			dfs(e[i].to);
			vis[e[i].to] = 0, dis[e[i].to] = tt, g.pop_back();
		}
	}
	return;
}

void solve_flower()
{
	while(q--)
	{
		cin >> u >> v;
		if(u == v) cout << max(a[u], 0ll) << '\n';
		else if(u == 1) cout << min(a[u], max(a[v], mp[{u, v}])) << '\n';
		else if(v == 1) cout << min(a[v], max(a[u], mp[{v, u}])) << '\n';
		else cout << min(a[u], min(max(a[1], mp[{u, 1}]), max(a[v], mp[{u, 1}] + mp[{1, v}]))) << '\n';
	}
	return;
}

signed main()
{
	freopen("poitry.in", "r", stdin);
	freopen("poitry.out", "w", stdout);
	ios :: sync_with_stdio(false);
	cin.tie(0), cout.tie(0);
	cin >> n >> q;
	for(int i = 1; i <= n; i++) cin >> a[i];
	for(int i = 1; i < n; i++)
	{
		cin >> u >> v >> w;
		add_edge(u, v, w);
		add_edge(v, u, w);
		flag_flower &= (u == 1);
		mp[{u, v}] = mp[{v, u}] = 1;
	}
	if(flag_flower) {solve_flower(); return 0;}
	while(q--)
	{
		cin >> u >> v;
		flag = 0, ans = inf, g.clear();
		memset(vis, 0, sizeof vis);
		memset(dis, 0x3f, sizeof dis);
		g.push_back(u), vis[u] = 1, dis[u] = 0;
		dfs(u);
		cout << ans << '\n';
	}
	return 0;
}