#include<bits/stdc++.h>
#define int long long
using namespace std;
const int N=2e6+5000;

int n,q,w[N],d[N],mp[N],siz[N],a[N],b[N],dep[N],cnt,head[N],fa[N],top[N],son[N],m;

struct node
{
    int u,v,w,nxt;
}e[N];

void dfs(int x)
{
    siz[x]=1;d[x]=d[fa[x]]+1;
    for(int i=head[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if(v==fa[x])continue;
        dep[v]=dep[x]+e[i].w;fa[v]=x;
        dfs(v);siz[x]+=siz[v];
        if(siz[v]>siz[son[x]])son[x]=v;
    }
}

void dfs2(int x,int topp)
{
    // top[x]=topp;cout<<x<<' '<<topp<<'\n';
    top[x]=topp;
    for(int i=head[x];i;i=e[i].nxt)
    {
        int v=e[i].v;
        if(v==fa[x])continue;
        dfs2(v,v==son[x]?topp:v);
    }
}

int LCA(int u,int v)
{
    while(top[u]!=top[v])
    {
        if(d[top[u]]<d[top[v]])swap(u,v);
        u=fa[top[u]];
    }
    return d[u]<d[v]?u:v;
}

int len(int u,int v)
{
    if(!u||!v)return 0;
    return dep[u]+dep[v]-2*dep[LCA(u,v)];
}

main()
{
    // freopen("in.txt","r",stdin);
    cin>>n>>q;
    for(int i=1;i<=n;i++)
    {
        cin>>w[i];
        if(w[i]<=n)mp[w[i]]=i;
    }
    for(int i=1;i<n;i++)
    {
        int u,v,w;
        cin>>u>>v>>w;
        e[++cnt]=(node){u,v,w,head[u]};head[u]=cnt;
        e[++cnt]=(node){v,u,w,head[v]};head[v]=cnt;
    }
    dfs(1);dfs2(1,1);while(mp[m++]);
    a[0]=b[0]=mp[0];
    for(int i=1;i<m;i++)
    {
        int x=a[i-1],y=b[i-1],w=len(x,y),t=mp[i],r=len(x,t)>len(y,t)?x:y;
        if(len(r,t)>w)a[i]=r,b[i]=t;else a[i]=x,b[i]=y;
    }
    while(q--)
    {
        int x,d;cin>>x>>d;
        int l=0,r=m-1,ans=m;
        while(l<=r)
        {
            int mid=(l+r)>>1;
            if(len(a[mid],x)>d||len(b[mid],x)>d)ans=mid,r=mid-1;
            else l=mid+1;
        }
        cout<<ans<<'\n';
    }
}