#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N=5e5+10,inf=1e18;
int n,q,a[N],u,v,w,x,k,ans[N],s[N],root,nowmin=-1,rt,now;
vector <array<int,2>> Q[N];
vector <array<int,2>> edge[N];
bool vis[N];
void init(int u,int fa){
	s[u]=1;
	for(int i=0;i<edge[u].size();i++){
		int v=edge[u][i][0];
		if(v==fa||vis[v])continue;
		init(v,u);s[u]+=s[v];
	}
}
void find(int u,int fa){
	if(fa==0)nowmin=1e9,init(u,fa),rt=u;
	int MAX=-1;
	for(int i=0;i<edge[u].size();i++){
		int v=edge[u][i][0];
		if(v==fa||vis[v])continue;
		find(v,u);MAX=max(MAX,s[v]);
	}
	MAX=max(MAX,s[rt]-s[u]);
	if(nowmin>MAX){
		nowmin=MAX;
		root=u;
	}
}
int tree[N<<2];
void pushup(int rt){tree[rt]=max(tree[rt<<1],tree[rt<<1|1]);}
void update(int rt,int left,int right,int x,int y){
	if(left==right){tree[rt]=y;return;}
	int mid=(left+right)>>1;
	if(x<=mid)update(rt<<1,left,mid,x,y);
	else update(rt<<1|1,mid+1,right,x,y);
	pushup(rt);
}
int query(int rt,int left,int right,int x){
	if(left==right)return left;
	int mid=(left+right)>>1;
	if(tree[rt<<1]>x)return query(rt<<1,left,mid,x);
	else return query(rt<<1|1,mid+1,right,x);
}
void upd(int u,int fa,int op,int dep){
	if(a[u]<=n){
		if(op==1)update(1,0,n,a[u],dep);
		else update(1,0,n,a[u],-inf);
	}
	for(auto it:edge[u]){
		int v=it[0],w=it[1];
		if(vis[v]||v==fa)continue;
		upd(v,u,op,dep+w);
	}
}
void calc(int u,int fa,int dep){
	for(auto it:Q[u]){
		int k=it[0],id=it[1];
		ans[id]=min(ans[id],query(1,0,n,k-dep));
	}
	for(auto it:edge[u]){
		int v=it[0],w=it[1];
		if(vis[v]||v==fa)continue;
		calc(v,u,dep+w);
	}
}
void solve(int u){
	vis[u]=true;
	for(int i=0;i<edge[u].size();i++){
		int v=edge[u][i][0];int w=edge[u][i][1];
		if(vis[v])continue;
		upd(v,0,1,w);
	}
	for(auto it:Q[u]){
		int k=it[0],id=it[1];
		ans[id]=min(ans[id],query(1,0,n,k));
	}
	if(a[u]<=n)update(1,0,n,a[u],0);
	for(int i=0;i<edge[u].size();i++){
		int v=edge[u][i][0];int w=edge[u][i][1];
		if(vis[v])continue;
		upd(v,0,-1,w);
		calc(v,0,w);
		upd(v,0,1,w);
	}
	if(a[u]<=n)update(1,0,n,a[u],-inf);
	for(int i=0;i<edge[u].size();i++){
		int v=edge[u][i][0];int w=edge[u][i][1];
		if(vis[v])continue;
		upd(v,0,-1,w);
	}
	for(int i=0;i<edge[u].size();i++){
		int v=edge[u][i][0];
		if(vis[v])continue;
		find(v,0);solve(root);
	}
}
signed main(){
	ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	memset(tree,-0x3f,sizeof(tree));
	memset(ans,0x3f,sizeof(ans));
	cin>>n>>q;
	vector <int> p;
	for(int i=1;i<=n;i++)cin>>a[i],p.push_back(a[i]);
	sort(p.begin(),p.end());
	if(p[0]==0){
		p.push_back(2e9);
		for(int i=0;i+1<p.size();i++){
			if(p[i]+1!=p[i+1]){
				for(int j=1;j<=q;j++)
					ans[j]=p[i]+1;
				break;
			}
		}
	}else memset(ans,0,sizeof(ans));
	for(int i=1;i<n;i++){
		cin>>u>>v>>w;
		edge[u].push_back({v,w});
		edge[v].push_back({u,w});
	}
	for(int i=1;i<=q;i++){
		cin>>x>>k;
		Q[x].push_back({k,i});
	}
	find(1,0);
	solve(root);
	for(int i=1;i<=q;i++)
		cout<<ans[i]<<"\n";
	return 0;
}