#include<bits/stdc++.h>
#define ll long long
#define pii pair<int,int>
#define lowbit(x) (x&-x)
using namespace std;
inline int read() {
	int x=0,f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-') f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') {x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}
	return x*f;
}
inline ll Read() {
	ll x=0;
	int f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-') f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') {x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}
	return x*f;
}
int w[500005];
vector<pii>e[500005];
int f[500005][20],dep[500005];
int s[500005],t[500005];
ll dis[500005][20];
ll dt[500005];
void dfs(int x,int fa,int d){
	dep[x]=dep[fa]+1;
	f[x][0]=fa;
	dis[x][0]=d;
	for(int i=1;i<20;i++){
		f[x][i]=f[f[x][i-1]][i-1];
		dis[x][i]=dis[x][i-1]+dis[f[x][i-1]][i-1];
	}
	for(auto u:e[x]){
		if(u.first==fa)continue;
		dfs(u.first,x,u.second);
	}
}
int lca(int u,int v){
	if(dep[u]<dep[v])swap(u,v);
	for(int i=19;i>=0;i--){
		if(dep[u]-dep[v]>=(1<<i)){
			u=f[u][i];
		}
	}
	if(u==v)return u;
	for(int i=19;i>=0;i--){
		if(f[u][i]!=f[v][i]){
			u=f[u][i];
			v=f[v][i];
		}
	}
	return f[u][0];
}
ll dist(int u,int v){
	ll d=0;
	if(dep[u]<dep[v])swap(u,v);
	for(int i=19;i>=0;i--){
		if(dep[u]-dep[v]>=(1<<i)){
			d+=dis[u][i];
			u=f[u][i];
		}
	}
	if(u==v)return d;
	for(int i=19;i>=0;i--){
		if(f[u][i]!=f[v][i]){
			d+=dis[u][i]+dis[v][i];
			u=f[u][i];
			v=f[v][i];
		}
	}
	return d+dis[u][0]+dis[v][0];
}
pii calc(int x,int y,int z){
	ll xy=dist(x,y),yz=dist(y,z),xz=dist(x,z);
	if(xy>=yz&&xy>=xz)return {x,y};
	if(yz>=xz)return {y,z};
	return {x,z};
}
void solve(){
	int n=read(),q=read();
	vector<pii>p;
	for(int i=1;i<=n;i++){
		w[i]=read();
		p.push_back({w[i],i});
	}
	for(int i=1;i<n;i++){
		int u=read(),v=read(),w=read();
		e[u].push_back({v,w});
		e[v].push_back({u,w});
	}
	dfs(1,0,0);
	sort(p.begin(),p.end());
	int sz=0;
	for(int i=0;i<n;i++){
		if(p[i].first!=i)break;
		sz++;
		int tl,tr;
		if(sz==1)tl=tr=p[i].second;
		else{
			pii tmp=calc(s[i],t[i],p[i].second);
			tl=tmp.first;
			tr=tmp.second;
		}
		s[sz]=tl;
		t[sz]=tr;
		dt[sz]=dist(tl,tr);
	}
	for(int i=1;i<=q;i++){
		int x=read();
		ll k=Read();
		int l=0,r=sz;
		while(l<r){
			int mid=l+r+1>>1;
			if(k>=dt[mid]&&dist(x,s[mid])<=k&&dist(x,t[mid])<=k)l=mid;
			else r=mid-1;
		}
		printf("%d\n",r);
	}
}
int main(){
    int t=1;
    //scanf("%d",&t);
    while(t--)solve();
    return 0;
}