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

typedef long long ll;

const int MAXN=5e5,LOGN=18;

inline ll Read()
{
	ll res;char c;
	while(1) {c=getchar();if('0'<=c && c<='9') {res=c-'0';break;}}
	while(1) {c=getchar();if('0'<=c && c<='9') res=res*10+c-'0';else break;}
	return res;
}

int n,q,A[MAXN+5];
int Q[MAXN+5],ALL,pre[MAXN+5][2];
vector< pair<int,int> > Tree[MAXN+5];

inline bool cmp(int a,int b) {return A[a]<A[b];}

int fa[MAXN+5],DFN[MAXN+5],tot;
ll dis[MAXN+5];
void CalMsg(int now)
{
	DFN[now]=++tot;
	for(int i=0,rear;i<Tree[now].size();i++)
	{
		rear=Tree[now][i].first;
		if(rear==fa[now]) continue;
		fa[rear]=now;
		dis[rear]=dis[now]+Tree[now][i].second;
		CalMsg(rear);
	}
}
int lg[MAXN+5],ST[LOGN+1][MAXN+5]; 
inline void Build()
{
	for(int i=2;i<=n;i++) lg[i]=lg[i-1]+((1<<(lg[i-1]+1))<=i);
	for(int i=1;i<=n;i++) ST[0][DFN[i]]=i;
	for(int i=1;(1<<i)<=n;i++)
		for(int j=1;j+(1<<i)-1<=n;j++)
		{
			int a=ST[i-1][j],b=ST[i-1][j+(1<<(i-1))];
			ST[i][j]=(dis[a]<dis[b] ? a : b);
		}
}
inline int LCA(int a,int b)
{
	if(a==b) return a;
	a=DFN[a],b=DFN[b];
	if(a>b) swap(a,b);
	int w=lg[b-a],x=ST[w][a+1],y=ST[w][b-(1<<lg[b-a])+1];
	if(dis[x]<dis[y]) return fa[x];
	return fa[y];
}
inline ll GetDis(int a,int b) {return dis[a]+dis[b]-2*dis[LCA(a,b)];}

int main()
{
	n=Read(),q=Read();
	for(int i=1;i<=n;i++) A[i]=Read(),Q[i]=i;
	sort(Q+1,Q+n+1,cmp);
	for(int i=1;i<=n;i++)
		if(A[Q[i]]==ALL) ++ALL;
		else break;
	for(int i=1,a,b,c;i<n;i++)
	{
		a=Read(),b=Read(),c=Read();
		Tree[a].push_back(make_pair(b,c));
		Tree[b].push_back(make_pair(a,c));
	}
	CalMsg(1),Build();
	pre[1][0]=pre[1][1]=Q[1];
	for(int i=2;i<=n;i++)
	{
		pre[i][0]=pre[i-1][0],pre[i][1]=pre[i-1][1];
		if(GetDis(Q[i],pre[i-1][1])>GetDis(pre[i][0],pre[i][1]))
			pre[i][0]=Q[i],pre[i][1]=pre[i-1][1];
		if(GetDis(pre[i-1][0],Q[i])>GetDis(pre[i][0],pre[i][1]))
			pre[i][0]=pre[i-1][0],pre[i][1]=Q[i];
	}
	A[0]=n; 
	ll K;
	for(int X;q--;)
	{
		X=Read(),K=Read();
		int L=1,R=n;
		for(int mid;L<=R;)
		{
			mid=(L+R)>>1;
			if(GetDis(X,pre[mid][0])>K || GetDis(X,pre[mid][1])>K) R=mid-1;
			else L=mid+1;
		}
		printf("%d\n",min(ALL,A[Q[L]]));
	}
	return 0;
}