#include "bits/stdc++.h"
// @JASPER'S BOILERPLATE
using namespace std;
using ll = long long;

#ifdef JASPER
#include "debug.h"
#else
#define debug(...) 166
#endif

const int N = 5e5 + 5;
const int LG = 20;

vector <pair <int, int>> adj[N];
int dep[N], up[LG][N], st[N];
int w[N];
ll dis[N];
int timer = 0;

int tour[2 * N], lg[2 * N];

int lca(int u, int v) {
    int l = st[u];
    int r = st[v];
    if (l > r)
        swap(l, r);
    int k = lg[r - l + 1];
    return (dep[up[k][l]] < dep[up[k][r - (1 << k) + 1]])? up[k][l] : up[k][r - (1 << k) + 1];
}
 
void build() {
    lg[1] = 0;
    for (int i = 2; i <= timer; i++)
        lg[i] = lg[i / 2] + 1;
    for (int i = 1; i <= timer; i++) 
        up[0][i] = tour[i];
 
    for (int k = 1; k < LG; k++)
        for (int i = 1; i + (1 << k) - 1 <= timer; i++)
            up[k][i] = (dep[up[k - 1][i]] < dep[up[k - 1][i + (1 << (k - 1))]])?
                        up[k - 1][i] : up[k - 1][i + (1 << (k - 1))];
}
 
void dfs(int u, int p) {
    st[u] = ++timer;
    tour[timer] = u;
    for (const auto &[l, v] : adj[u]) {
        if (v == p)
            continue;
        dis[v] = dis[u] + l;
        dep[v] = dep[u] + 1;
        dfs(v, u);
        tour[++timer] = u;
    }
}

ll get(int u, int v) {
	int p = lca(u, v);
	return (dis[u] + dis[v] - 2LL * dis[p]);
}

int id1[N], id2[N];

signed main() {
    cin.tie(0) -> sync_with_stdio(0);
 
 	int n, q;
	cin >> n >> q;
	for (int i = 1; i <= n; ++i) cin >> w[i];
	for (int i = 1; i < n; ++i) {
		int u, v, l;
		cin >> u >> v >> l;
		adj[u].push_back({l, v});
		adj[v].push_back({l, u});
	}

	dfs(1, 0);
	build();

	vector <int> vis(n + 1, 0);
	vector <int> ord(n);

	for (int i = 1; i <= n; ++i) {
		if (w[i] <= n) vis[w[i]] = 1;
		ord[i - 1] = i;
	}

	sort(ord.begin(), ord.end(), [] (const int i, const int j) {
		return w[i] < w[j];
	});

	int mex = 0;
	while (vis[mex]) ++mex;

	id1[0] = id2[0] = ord[0];
	for (int i = 1; i < n; ++i) {
		int u = id1[i - 1], v = id2[i - 1];
		ll D = get(u, v);
		ll D1 = get(ord[i], u);
		ll D2 = get(ord[i], v);
		if (D1 > D2) {
			if (D1 > D) v = ord[i];
		}
		else if (D2 > D) u = ord[i];
		id1[i] = u;
		id2[i] = v;
	}

	for (int _q = 1; _q <= q; ++_q) {
		int x; ll k;
		cin >> x >> k;
		if (k == 0) {
			int ans = (w[x] == 0);
			cout << ans << "\n";	
			continue;	
		}

		ll l = 0, r = mex;
		while (l < r) {
			ll m = (l + r) / 2;
			if (max(get(id1[m], x), get(id2[m], x)) <= k) {
				l = m + 1;
			} 
			else 
				r = m;
		}

		cout << l << "\n";
	}

    return 0;
}