#include <bits/stdc++.h>

#define F(i, a, b) for (int i = a; i <= b; i ++)
#define G(i, a, b) for (int i = a; i >= b; i --)
#define max(a, b) ((a) > (b) ? (a) : (b))
#define min(a, b) ((a) < (b) ? (a) : (b))
#define mx(a, b) ((a) = max(a, b))
#define mn(a, b) ((a) = min(a, b))
#define get getchar()
#define putc putchar
#define outarr(a, L, R) { printf(#a"[%d..%d] = ", L, R); F(i, L, R) W(a[i]), putc(' ') ; putc('\n'); }
#define out1(x) { printf(#x" = "), W(x), putc('\n'); }
#define out2(x, y) { printf(#x" = "), W(x), printf(" "#y" = "), W(y), putc('\n'); }
#define out3(x, y, z) { printf(#x" = "), W(x), printf(" "#y" = "), W(y), printf(" "#z" = "), W(z), putc('\n'); }

using namespace std;

template <typename Int>
void R(Int &x) {
	char c = get; x = 0; Int t = 1;
	for (; !isdigit(c); c = get) t = (c == '-' ? -1 : t);
	for (; isdigit(c); x = (x << 3) + (x << 1) + c - '0', c = get); x *= t;
}
template <typename Int>
void W(Int x) {
	if (x < 0) { putc('-'); x = - x; }
	if (x > 9) W(x / 10); putc(x % 10 + '0');
}

#define pb push_back
#define ll long long

const int N = 1e6 + 10;
int n, q, w[N], u, v, l, x, k;

struct node {
	int x, y;
	friend bool operator < (node a, node b) { return a.x < b.x; }
} D[N], E[N];
struct edge {
	int x, l;
} ; vector <edge> e[N];

int cnt, d[N], fir[N], dep[N], _[N], f[N][20], dis[N];
int Min(int x, int y) {
	return dep[x] < dep[y] ? x : y;
}
int Lca(int x, int y) {
	x = fir[x], y = fir[y]; if (x > y) swap(x, y);
	int k = _[y - x + 1];
	return Min(f[x][k], f[y - (1 << k) + 1][k]);
}
void Init() {
	F(i, 2, cnt) _[i] = _[i >> 1] + 1;
	F(i, 1, cnt) f[i][0] = d[i];
	F(j, 1, 19) for (int i = 1; i + (1 << j) - 1 <= cnt; i ++)
		f[i][j] = Min(f[i][j - 1], f[i + (1 << (j - 1))][j - 1]);
}
void Dfs(int k, int fa) {
	d[++ cnt] = k, fir[k] = cnt, dep[k] = dep[fa] + 1;
	for (auto [ x, l ] : e[k])
		if (x ^ fa)
			dis[x] = dis[k] + l, Dfs(x, k), d[++ cnt] = k;
}
int Dis(int x, int y) {
	if (!x || !y) return 0;
	return dis[x] + dis[y] - 2 * dis[Lca(x, y)];
}

int main() {
//	freopen("data.in","r",stdin);

	R(n), R(q);
	F(i, 1, n) R(D[i].x), D[i].y = i;
	F(i, 1, n - 1) R(u), R(v), R(l), e[u].pb({v, l}), e[v].pb({u, l});

	Dfs(1, 0);
	Init();
//	outarr(dis, 1, n);
//	out1(Dis(4,5));

	sort(D + 1, D + n + 1);
	int m = 0; D[0].x = - 1;
	F(i, 1, n) {
		if (D[i].x != D[i - 1].x + 1) break;
		m = i;
		E[i] = E[i - 1];
		if (i == 1) E[i].x = D[i].y;
		if (i == 2) E[i].y = D[i].y;
		if (i > 2) {
			int z1 = Dis(E[i].x, E[i].y);
			int z2 = Dis(E[i].x, D[i].y);
			int z3 = Dis(E[i].y, D[i].y);
			if (z1 < max(z2, z3)) {
				if (z2 > z3)
					E[i].y = D[i].y;
				else
					E[i].x = D[i].y;
			}
		}
	}

	F(i, 1, q) {
		R(x), R(k);
		int l = 1, r = m, ans = 0;
		while (l <= r) {
			int md = (l + r) >> 1;
			if (max(Dis(E[md].x, x), Dis(E[md].y, x)) <= k)
				ans = md, l = md + 1;
			else
				r = md - 1;
		}
		W(ans), putc('\n');
	}
}