#include<bits/stdc++.h>
using namespace std;
const int N=500005;
int n,q;
int w[N];
vector<pair<int,int>>G[N];
int id[N],mex;
int dfn[N],Index;
int mn[N][20],lg2[N];
long long dis[N];
void dfs(int u,int father)
{
    dfn[u]=++Index;
    mn[Index][0]=father;
    for(auto [v,w]:G[u])
    {
        if(v==father) continue;
        dis[v]=dis[u]+w;
        dfs(v,u);
    }
    return;
}
int lca(int u,int v)
{
    if(u==v) return u;
    u=dfn[u],v=dfn[v];
    if(u>v) swap(u,v);
    u++;
    int d=lg2[v-u+1];
    if(dfn[mn[u][d]]<dfn[mn[v-(1<<d)+1][d]]) return mn[u][d];
    else return mn[v-(1<<d)+1][d];
}
void init_lca(int n)
{
    lg2[0]=-1;
    for(int i=1;i<=n;i++)
        lg2[i]=lg2[i/2]+1;
    for(int j=1;(1<<j)<=n;j++)
        for(int i=1;i+(1<<j)-1<=n;i++)
            if(dfn[mn[i][j-1]]<dfn[mn[i+(1<<(j-1))][j-1]]) mn[i][j]=mn[i][j-1];
            else mn[i][j]=mn[i+(1<<(j-1))][j-1];
    return;
}
long long query_dis(int u,int v)
{
    return dis[u]+dis[v]-dis[lca(u,v)]*2;
}
int p1[N],p2[N];
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr),cout.tie(nullptr);
    cin>>n>>q;
    for(int i=1;i<=n;i++)
        cin>>w[i];
    for(int i=1;i<n;i++)
    {
        int u,v,w;
        cin>>u>>v>>w;
        G[u].emplace_back(v,w);
        G[v].emplace_back(u,w);   
    }
    Index=0;
    dfs(1,0);
    init_lca(n);
    for(int i=1;i<=n;i++)
        id[i]=i;
    sort(id+1,id+n+1,[=](const int &x,const int &y){return w[x]<w[y];});
    w[0]=-1;
    for(int i=1;i<=n;i++)
    {
        if(w[id[i]]!=w[id[i-1]]+1)
        {
            mex=w[id[i-1]]+1;
            break;
        }
        int u=id[i];
        int val=w[u];
        if(val>0) p1[val]=p1[val-1],p2[val]=p2[val-1];
        else p1[val]=p2[val]=0;
        if(!p1[val]) p1[val]=u;
        else if(!p2[val]) p2[val]=u;
        else
        {
            if(query_dis(u,p1[val])>query_dis(p1[val],p2[val])) p2[val]=u;
            else if(query_dis(u,p2[val])>query_dis(p1[val],p2[val])) p1[val]=u;
        }
    }
    while(q--)
    {
        int u;
        long long k;
        cin>>u>>k;
        int l=0,r=mex,ans=mex;
        auto check=[=](int x)->bool
        {
            long long d=0;
            if(p1[x]) d=max(d,query_dis(p1[x],u));
            if(p2[x]) d=max(d,query_dis(p2[x],u));
            return d>k;
        };
        while(l<=r)
        {
            int mid=(l+r)>>1;
            if(check(mid)) ans=mid,r=mid-1;
            else l=mid+1;
        }
        cout<<ans<<"\n";
    }
    return 0;
}