#include <cstdio>
#include <vector>
#include <algorithm>

#define X first
#define Y second
#define PB push_back

using namespace std;

typedef long long ll;
typedef vector < int > vi;
typedef pair < int, int > pii;

const int N = 5e5 + 500;

vector < pii > v[N];
vector < int > comp;
int siz[N], blok[N], col[N], n, q;
ll dis[N];

void colour(int x, int lst, int cur) {
	col[x] = cur;
	for(auto [y, w] : v[x])
		if(y != lst && !blok[y]) colour(y, x, cur);
}

void dfs(int x, int lst) {
	siz[x] = 1; comp.PB(x);
	for(auto [y, w] : v[x]) {
		if(y != lst && !blok[y]) {
			dis[y] = dis[x] + w;
			dfs(y, x);
			siz[x] += siz[y];
		}
	}
}

bool cmp(int A, int B) {
	return dis[A] > dis[B];
}


ll qdis[N];
int ans[N];
int qno[N], val[N];

bool cmp2(int A, int B) {
	return qdis[A] - dis[qno[A]] > qdis[B] - dis[qno[B]];
}

void rek(int xx, vector < int > qv) {
	dfs(xx, xx); 
	int x = xx;
	for(int t : comp)
		if(siz[t] < siz[x] && 2 * siz[t] >= (int)comp.size())
			x = t;
	comp.clear();
	dis[x] = 0; dfs(x, x); 
	sort(comp.begin(), comp.end(), cmp);
	for(int i = 0;i < (int)v[x].size();i++) {
		if(!blok[v[x][i].X]) colour(v[x][i].X, x, i);
	}
	col[x] = -1;
	int odg1 = -1, odg2 = -1, j = 0;
	vector < vi > sQ((int)v[x].size());
	sort(qv.begin(), qv.end(), cmp2);
	for(int i = 0;i < (int)comp.size();i++) {
		int c = comp[i];
		while(j < (int)qv.size() && qdis[qv[j]] - dis[qno[qv[j]]] >= dis[c]) {
			if(odg1 != -1 && col[odg1] != col[qno[qv[j]]]) {
				ans[qv[j]] = min(ans[qv[j]], val[odg1]);
			}	
			if(odg2 != -1 && col[odg2] != col[qno[qv[j]]]) {
				ans[qv[j]] = min(ans[qv[j]], val[odg2]);
			}
			if(qno[qv[j]] != x) sQ[col[qno[qv[j]]]].PB(qv[j]);
			j++;
		}
		if(odg1 == -1 || val[c] < val[odg1]) 
			swap(c, odg1);
		if(odg2 == -1 || val[c] < val[odg2]) 
			swap(c, odg2);
	}
	while(j < (int)qv.size()) {
			if(odg1 != -1 && col[odg1] != col[qno[qv[j]]]) {
				ans[qv[j]] = min(ans[qv[j]], val[odg1]);
			}	
			if(odg2 != -1 && col[odg2] != col[qno[qv[j]]]) {
				ans[qv[j]] = min(ans[qv[j]], val[odg2]);
			}
			if(qno[qv[j]] != x) sQ[col[qno[qv[j]]]].PB(qv[j]);
			j++;
		}
	blok[x] = 1;
	for(int i = 0;i < (int)v[x].size();i++) {
		if(!blok[v[x][i].X]) {
			rek(v[x][i].X, sQ[i]);
		}
	}
}


int main(){
	scanf("%d%d", &n, &q);
	vi smece;
	for(int i = 1;i <= n;i++) {
		scanf("%d", val + i); smece.PB(val[i]);
	}
	sort(smece.begin(), smece.end());
	int bar = 0;
	while(bar < n && smece[bar] == bar) bar++;
	for(int i = 1;i < n;i++) {
		int a, b, c; scanf("%d%d%d", &a, &b, &c);
		v[a].PB({b, c}); v[b].PB({a, c});
	}
	smece.clear();
	for(int i = 0;i < q;i++) {
		smece.PB(i); ans[i] = bar;
		scanf("%d%lld", qno + i, qdis + i);
	}
	sort(smece.begin(), smece.end(), cmp2);
	rek(1, smece);
	for(int i = 0;i < q;i++)
		printf("%d\n", ans[i]);
	return 0;
}