#include<iostream>
#include<cstdio>
#include<algorithm>
#define int long long
using namespace std;
typedef long double ld;
typedef long long ll;
const int MX=500010;

int N, Q;
int w[MX];
int head[MX], cnt=0;
int son[MX], fa[MX], top[MX], dep[MX], siz[MX], pat[MX];
int lp[MX], rp[MX];
bool ext[MX];
int read()
{
    int r=0, f=1; char ch=getchar();
    while(ch<'0'||ch>'9') {if(ch=='-') f=-1; ch=getchar();}
    while(ch>='0'&&ch<='9') {r=r*10+ch-'0'; ch=getchar();}
    return r*f;
}
struct edge{int nxt, to, c;}e[2*MX];
inline void ae(int u, int v, int c) {e[++cnt].to=v; e[cnt].nxt=head[u]; head[u]=cnt; e[cnt].c=c;}
struct node
{
    int p, c;
    bool operator < (const node &a)const {return c<a.c;}
}pt[MX];
void dfs1(int x, int f, int D)
{
    fa[x]=f; dep[x]=D; siz[x]=1;
    for(int i=head[x];i;i=e[i].nxt)
    {
        int y=e[i].to;
        if(y==f) continue;
        pat[y]=pat[x]+e[i].c;
        dfs1(y,x,D+1);
        siz[x]+=siz[y]; 
        if(siz[y]>siz[son[x]]) son[x]=y;
    }
}
void dfs2(int x, int topf)
{
    top[x]=topf; 
    if(!son[x]) return;
    dfs2(son[x],topf);
    for(int i=head[x];i;i=e[i].nxt)
    {
        int y=e[i].to;
        if(y==fa[x]||y==son[x]) continue;
        dfs2(y,y);
    }
}
inline int lca(int x, int y)
{
    while(top[x]!=top[y])
    {
        if(dep[top[x]]<dep[top[y]]) swap(x,y);
        x=fa[top[x]];
    }
    if(dep[x]>dep[y]) swap(x,y); return x;
}
int dis(int x, int y)
{
    int l=lca(x,y);
    return pat[x]+pat[y]-2*pat[l];
}
signed main()
{
    // freopen("testdata.in","r",stdin);
    N=read(); Q=read();
    for(int i=1;i<=N;i++) 
    {
        w[i]=read();
        pt[i]={i,w[i]};
        if(w[i]<=5e5+5) ext[w[i]]=1; 
    }
    sort(pt+1,pt+1+N);
    for(int i=1;i<N;i++)
    {
        int u=read(), v=read(), c=read();
        ae(u,v,c); ae(v,u,c);
    }
    dfs1(1,0,1);
    dfs2(1,1);
    lp[1]=rp[1]=pt[1].p;
    for(int i=2;i<=N;i++)
    {
        lp[i]=lp[i-1]; rp[i]=rp[i-1];
        if(dis(lp[i],rp[i])<dis(pt[i].p,rp[i])) lp[i]=pt[i].p;
        if(dis(lp[i],rp[i])<dis(pt[i].p,lp[i])) rp[i]=pt[i].p;
    }
    // cout << pat[4] << " " << pat[5] << '\n';
    // cout << "dis (1,5)=" << dis(1,5) << ", dis(4,5)=" << dis(4,5) << '\n';
    for(int i=1;i<=N;i++)
    {
        // cout << "p=" << pt[i].p << ", lp=" << lp[i] << ", rp=" << rp[i] << '\n';
    }
    int lim=MX;
    for(int i=0;i<=5e5+5;i++) 
        if(!ext[i]) {lim=i; break;}
    while(Q--)
    {
        int x=read(), k=read();
        int l=0, r=lim, ans=0;
        while(l<=r)
        {
            int mid=(l+r)>>1; //w[i]<=mid full covered
            // cout << "mid=" << mid << ", lp=" << lp[mid+1] << ", rp=" << rp[mid+1] << '\n';
            if(dis(lp[mid+1],x)<=k&&dis(rp[mid+1],x)<=k) ans=mid+1, l=mid+1;
            else r=mid-1;
        }
        cout << ans << '\n';
    }
    return (0-0);
}