#include<bits/stdc++.h>
using namespace std;
#define cs const
#define re register
#define pb push_back
#define pii pair<int,int>
#define ll long long
#define fi first
#define se second
#define bg begin
#define gc getchar
inline int read(){
	char ch=gc();
	int res=0;bool f=1;
	while(!isdigit(ch))f^=ch=='-',ch=gc();
	while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
	return f?res:-res;
}
inline ll readll(){
	char ch=gc();
	ll res=0;bool f=1;
	while(!isdigit(ch))f^=ch=='-',ch=gc();
	while(isdigit(ch))res=(res+(res<<2)<<1)+(ch^48),ch=gc();
	return f?res:-res;
}
template<typename tp>inline void chemx(tp &a,tp b){(a<b)?(a=b):0;}
template<typename tp>inline void chemn(tp &a,tp b){(a>b)?(a=b):0;}


cs int N=500005;

int n,q,maxn,rt;
int w[N];
int sz[N],son[N],vs[N];
struct F{
	int f,pf;
	ll d;
	F(int _f=0,int _p=0,ll _d=0):f(_f),pf(_p),d(_d){}
};vector<F>fa[N];
vector<pii> e[N];

struct node{
	int w,p;
	ll d;
	node(int _f=0,int _p=0,ll _d=0):w(_f),p(_p),d(_d){}
	friend bool operator <(cs node &a,cs node &b){
		return a.d<b.d;
	}
};
vector<node> d[N];
struct info{
	pii x,y;
	void init(node c){
		x=y=pii(c.w,c.p);
	}
};
info merge(info x,node c){
	pii y=pii(c.w,c.p);
	if(y.fi<x.x.fi)x.y=x.x,x.x=y;
	else if(y.fi<x.y.fi)x.y=y;
	return x;
}
vector<info> f1[N];
void getrt(int u,int f){
	sz[u]=1,son[u]=0;
	for(pii x:e[u])if(x.fi!=f&&!vs[x.fi]){
		getrt(x.fi,u),sz[u]+=sz[x.fi];
		chemx(son[u],sz[x.fi]);
	}
	son[u]=max(son[u],maxn-sz[u]);
	if(son[u]<son[rt])rt=u;
}

void givefa(int u,int f,ll dep,int pf,int ff){
	fa[u].pb(F(ff,pf,dep));
	d[ff].pb(node(w[u],(u==ff)?-1:pf,dep));

	for(int i=0;i<e[u].size();i++){
		int v=e[u][i].fi;
		if(v==f||vs[v])continue;
		givefa(v,u,dep+e[u][i].se,(u==ff)?v:pf,ff);
	}
}
void init(int u){
	givefa(u,0,0,0,u);
	sort(d[u].begin(),d[u].end());
	int nn=d[u].size();
	f1[u].resize(nn);
	f1[u][nn-1].init(d[u].back());
	for(int i=nn-2;i>=0;i--)
	f1[u][i]=merge(f1[u][i+1],d[u][i]);
}
void solve(int u,int f){
	vs[u]=1;
	init(u);
	for(pii x:e[u])if(!vs[x.fi]){
		int v=x.fi;
		maxn=sz[v]>sz[u]?sz[f]-sz[u]:sz[v];
		getrt(v,rt=0);
		solve(rt,u);
	}
}
int calc(int u,int pf,ll dis){
	int l=0,r=f1[u].size()-1,res=-1;
	while(l<=r){
		int mid=(l+r)/2;
		if(d[u][mid].d>dis)res=mid,r=mid-1;
		else l=mid+1;
	}
	if(res==-1)return 2e9;
	if(f1[u][res].x.se==pf)return f1[u][res].y.fi;
	return f1[u][res].x.fi;
}
int query(int u,ll k){
	int res=2e9;
	for(int i=fa[u].size()-1;~i;i--){
		F x=fa[u][i];
		res=min(res,calc(x.f,x.pf,k-x.d));
	}
	return res;
}

int main(){
	#ifdef Stargazer
	freopen("1.in","r",stdin);
	#endif
	n=read(),q=read();
	map<int,int>visit;
	int mnans=0;
	for(int i=1;i<=n;i++)w[i]=read(),visit[w[i]]=1;
	for(int i=0;i<=n+1;i++)if(!visit[i]){
		mnans=i;break;
	}
	for(int i=1;i<n;i++){
		int u=read(),v=read(),w=read();
		e[u].pb(pii(v,w));
		e[v].pb(pii(u,w));
	}
	sz[0]=son[0]=maxn=n;
	getrt(1,rt=0);
	solve(rt,0);
	while(q--){
		int x=read();ll k=readll();
		cout<<min(query(x,k),mnans)<<'\n';
	}
}