#include<bits/stdc++.h>
using namespace std;
typedef long long LL;
const int N=5e5+10;
//anly the compx


int n,q,w[N],p[N],Log[2*N],mex;
pair<int,int>d[N];


int head[N],to[2*N],nxt[2*N],ww[2*N],tot;
void add(int x,int y,int c){
    tot++, to[tot]=y, nxt[tot]=head[x], ww[tot]=c, head[x]=tot;
}

int euler[2*N],edfn,in[N],dep[N];
LL dist[N];
void dfs(int x,int ff){
    in[x]=++edfn, euler[edfn]=x;
    for(int i=head[x];i;i=nxt[i]){
        int y=to[i];
        if(y==ff)continue;
        dep[y]=dep[x]+1;
        dist[y]=dist[x]+ww[i];
        dfs(y,x);
        euler[++edfn]=x;
    }
}

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

int fa[2*N][30];
void ST(){
    for(int i=1;i<=edfn;i++)fa[i][0]=euler[i], Log[i]=log(i)/log(2);
    int len=Log[edfn];
    for(int j=1;j<=len;j++)
        for(int i=1;i+(1<<j)-1<=edfn;i++)
            fa[i][j]=cmp(fa[i][j-1],fa[i+(1<<j-1)][j-1]);
}

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

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

int main(){
    scanf("%d%d",&n,&q);
    for(int i=1;i<=n;i++)scanf("%d",&w[i]),p[i]=i;
    sort(p+1,p+1+n,[](int x,int y){return w[x]<w[y];});
    mex=n;
    for(int i=1;i<=n;i++)if(w[p[i]]!=i-1){mex=i-1; break;}

    for(int i=1;i<=n-1;i++){
        int x,y,z;
        scanf("%d%d%d",&x,&y,&z);
        add(x,y,z);
        add(y,x,z);
    }
    dfs(1,0); ST();
    for(int i=1;i<=n;i++){
        int x=p[i];
        if(i==1){
            d[i]={x,x};
            continue;
        }
        LL maxx=dis(d[i-1].first, d[i-1].second);
        d[i]=d[i-1];
        if( maxx< dis(d[i-1].first,x) )maxx=dis( d[i-1].first, x ), d[i]={ d[i-1].first, x };
        if( maxx< dis(d[i-1].second,x) )maxx=dis( d[i-1].second, x ), d[i]={ d[i-1].second, x };
    }


    //for(int i=1;i<=n;i++)printf("%d %d\n",d[i].first,d[i].second);


    while(q--){
        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( dis(d[mid].first, x), dis(d[mid].second, x) );


            //printf("mid:%lld now:%lld\n",mid,now);


            if(now>k)r=mid;
            else l=mid+1;
        }
        if(n==1&&k==0)printf("%d\n",mex);
        else printf("%d\n",min(w[p[l]],mex));
    }
    return 0;
}
/*
5 4
3 9 0 1 2
1 2 10
3 1 4
3 4 3
3 5 2
3 0
1 0
4 6
4 7
*/