#include <stdio.h>
#include <string.h>

#include <set>
#include <vector>
#include <algorithm>

#define LOG(FMT...) fprintf(stderr, FMT)

#define eb emplace_back
#define em emplace

using namespace std;

typedef long long LL;
constexpr int N = 500005, M = 1000005;

void cmin(int &x, int y) {
	if (x > y) {
		x = y;
	}
}

void cmax(int &x, int y) {
	if (x < y) {
		x = y;
	}
}

int n, m, res1, a[N];
int h[N], e[M], ne[M], idx;
LL w[M];

void add(int x, int y, LL c) {
	ne[++idx] = h[x], h[x] = idx, e[idx] = y, w[idx] = c;
}

int Rt, rt, maxv;
int fa[N], de[N];
LL dis[20][N];
int col[20][N], idc;
struct Dat {
	LL d; int c, v, w;
	Dat(LL _d, int _c, int _v) : d(_d), c(_c), v(_v), w(0x7f7f7f7f) {}
	void upd(const Dat &t) {
		if (t.c == c) {
			cmin(v, t.v);
		} else if (t.v < v) {
			w = v, v = t.v, c = t.c;
		} else {
			cmin(w, t.v);
		}
	}
	bool operator < (const Dat &t) const {
		return d < t.d;
	}
};
vector<Dat> seq[N];
bool was[N];

int getsz(int x, int fat) {
	int ret = 1;
	for (int i = h[x]; i; i = ne[i]) {
		int y = e[i];
		if (y == fat || was[y]) {
			continue;
		}
		ret += getsz(y, x);
	}
	return ret;
}

int center(int x, int fat, int sz) {
	int v = 0, s = 1;
	for (int i = h[x]; i; i = ne[i]) {
		int y = e[i];
		if (y == fat || was[y]) {
			continue;
		}
		int t = center(y, x, sz);
		s += t, cmax(v, t);
	}
	cmax(v, sz - s);
	if (v < maxv) {
		maxv = v, rt = x;
	}
	return s;
}

int dep;

void dfs1(int x, int fat, LL d, vector<Dat> &v) {
	col[dep][x] = idc;
	dis[dep][x] = d;
	v.eb(d, idc, a[x]);
	for (int i = h[x]; i; i = ne[i]) {
		int y = e[i];
		if (y == fat || was[y]) {
			continue;
		}
		dfs1(y, x, d + w[i], v);
	}
}

int build(int x) {
	maxv = N;
	center(x, 0, getsz(x, 0));
	x = rt;
	was[x] = true;
	de[x] = dep;
	vector<Dat> &vs = seq[x];
	idc = 0;
	vs.eb(0ll, 0, a[x]);
	for (int i = h[x]; i; i = ne[i]) {
		int y = e[i];
		if (was[y]) {
			continue;
		}
		++idc;
		dfs1(y, x, w[i], vs);
	}
	sort(vs.begin(), vs.end());
	int c = -1, v = 0x7f7f7f7f, w = 0x7f7f7f7f;
	for (int i = (int)vs.size() - 1; ~i; --i) {
		auto &[ignore, tc, tv, tw] = vs[i];
		if (tc == c) {
			cmin(v, tv);
		} else if (tv < v) {
			w = v, v = tv, c = tc;
		} else {
			cmin(w, tv);
		}
		vs[i].c = c, vs[i].v = v, vs[i].w = w;
	}
	
	/* LOG("rt: %d\n", x);
	for (auto [d, c, v, w] : vs) {
		LOG("%lld %d %d %d\n", d, c, v, w);
	}
	LOG("\n"); */
	dep += 1;
	for (int i = h[x]; i; i = ne[i]) {
		int y = e[i];
		if (was[y]) {
			continue;
		}
		fa[build(y)] = x;
	}
	dep -= 1;
	return x;
}

int query() {
	int ret = res1;
	int x; LL d;
	scanf("%d%lld", &x, &d);
	for (int y = x; y; y = fa[y]) {
		LL *ds = dis[de[y]];
		int *co = col[de[y]];
		LL rs = d - ds[x];
		vector<Dat> &vs = seq[y];
		int k = upper_bound(vs.begin(), vs.end(), Dat(rs, 0, 0)) - vs.begin();
		/* for (auto [d, c, v, w] : vs) {
			LOG("%lld %d %d %d\n", d, c, v, w);
		}
		LOG("rs: %lld\n", rs);
		LOG("k: %d\n", k);
		exit(0); */
		if (k >= vs.size()) {
			continue;
		}
		const auto &[ignore, c, v, w] = vs[k];
		cmin(ret, c == co[x] ? w : v);
	}
	return ret;
}

int main() {
	scanf("%d%d", &n, &m);
	set<int> st;
	for (int x = 1; x <= n; ++x) {
		scanf("%d", a + x);
		st.em(a[x]);
	}
	for (; st.count(res1); ++res1);
	for (int i = 1, x, y; i < n; ++i) {
		LL c;
		scanf("%d%d%lld", &x, &y, &c);
		add(x, y, c), add(y, x, c);
	}
	Rt = build(1);
	/* for (int x = 1; x <= n; ++x) {
		LOG("%d ", fa[x]);
	}
	LOG("\n"); */
	while (m--) {
		printf("%d\n", query());
	}
	return 0;
}