#include<bits/stdc++.h>
#define fi first
#define se second
typedef long long ll;
typedef long long ll;
using namespace std;
const int N=5e5+10,M=N*2;

int head[N],ver[M],nxt[M],tot=1;
ll edge[M];
void add(int x,int y,ll z){
    ver[++tot]=y,edge[tot]=z,nxt[tot]=head[x],head[x]=tot;
}

pair<int,int>d[N];
int n,m,a[N],p[N];
int dfn[N<<1],cnt,fa[N<<1][25],dep[N],Log[N<<1];
ll dist[N];

void dfs(int x,int father){
    dfn[x]=++cnt,fa[cnt][0]=x;
    for(int i=head[x];i;i=nxt[i]){
        int y=ver[i];
        if(y==father)continue;
        dep[y]=dep[x]+1,dist[y]=dist[x]+edge[i];
        dfs(y,x);
        fa[++cnt][0]=x;
    }
}

int cmp(int x,int y){
    if(dep[x]<dep[y])return x;
    else return y;
}

void build(){
    for(int i=1;i<=cnt;i++)Log[i]=log2(i);

    for(int k=1;k<20;k++)
        for(int i=1;i+(1<<k)-1<=cnt;i++)
            fa[i][k]=cmp(fa[i][k-1],fa[i+(1<<(k-1))][k-1]);
}

int LCA(int x,int y){
    x=dfn[x],y=dfn[y];
    if(x>y)swap(x,y);
    int k=Log[y-x+1];
    return cmp(fa[x][k],fa[y-(1<<k)+1][k]);
}

ll get_dist(int x,int y){
    int lca=LCA(x,y);
    return dist[x]+dist[y]-2*dist[lca];
}

int main(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;i++)
        scanf("%d",&a[i]),p[i]=i;
    for(int i=1;i<n;i++){
        int x,y,z;
        scanf("%d%d%d",&x,&y,&z);
        add(x,y,z),add(y,x,z);
    }
    dfs(1,0),build();
    sort(p+1,p+n+1,[](int x,int y){
        return a[x]<a[y];
    });
    int mex=n;
    for(int i=1;i<=n;i++)
        if(a[p[i]]!=i-1){
            mex=i-1;
            break;
        }
    for(int i=1;i<=n;i++){
        int x=p[i];
        if(i==1)d[i]={x,x};
        else{
            int Max=get_dist(d[i-1].fi,d[i-1].se);
            d[i]=d[i-1];
            if(get_dist(d[i-1].fi,x)>Max)Max=get_dist(d[i-1].fi,x),d[i]={d[i-1].fi,x};
            if(get_dist(d[i-1].se,x)>Max)Max=get_dist(d[i-1].se,x),d[i]={d[i-1].se,x};
        }
        // printf("%d: %d %d %d\n",i,x,d[i].fi,d[i].se);
    }
    while(m--){
        int x;ll k;scanf("%d%lld",&x,&k);
        int l=1,r=n;
        while(l<r){
            int mid=(l+r)>>1;
            ll now=max(get_dist(d[mid].fi,x),get_dist(d[mid].se,x));
            if(now>k)r=mid;
            else l=mid+1;
        }
        printf("%lld\n",min(a[p[r]],mex));
    }
    return 0;
}