#include<bits/stdc++.h>
#define ll long long
#define int long long
#define fr(i,j,k) for(register int i=j;i<=k;++i)
#define rf(i,j,k) for(register int i=j;i>=k;--i)
#define foredge(i,j) for(register int i=head[j];i;i=e[i].nxt)
#define pb push_back
#define Times printf("Time:%.3lf\n",clock()/CLOCKS_PER_SEC)
#define pii pair<int,int>
#define mk make_pair
using namespace std;
inline int read(){
	int x=0;
	bool f=0;
	char c=getchar();
	while(!isdigit(c)) f|=(c=='-'),c=getchar();
	while(isdigit(c)) x=(x<<3)+(x<<1)+(c^48),c=getchar();
	return f?-x:x;
}
inline void write(int x){
    if(x<0){putchar('-');x=-x;}
    if(x>9)write(x/10);
    putchar(x%10+'0');
}
inline void writeln(int x){write(x); puts("");}
inline void writepl(int x){write(x); putchar(' ');}
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
inline int randfind(int l,int r){return rnd()%(r-l+1)+l;}
//inline void init(){
//	int t=read();
//	while(t--) work();
//}
const int Maxn=5e5+10;
int n,q;
struct node{
    int nxt,to,d;
}e[Maxn<<1];
int head[Maxn],cnt;
inline void add(int u,int v,int w){++cnt;e[cnt]=(node){head[u],v,w};head[u]=cnt;}
namespace LCA{
    int dfn[Maxn],f[25][Maxn<<2],dep[Maxn];
    int lg[Maxn<<2],idx,s[Maxn];
    inline int getmin(int x,int y){if(dep[x]<dep[y]) return x;return y;}
    inline void dfs(int x,int fa){
        dep[x]=dep[fa]+1;dfn[x]=++idx;f[0][idx]=x;
        for(register int i=head[x];i;i=e[i].nxt){
            int y;y=e[i].to;
            if(y!=fa) s[y]=s[x]+e[i].d,dfs(y,x),f[0][++idx]=x;
        }
    }
    inline int getlca(int x,int y){
        x=dfn[x],y=dfn[y];
        if(x>y) swap(x,y);
        int ln=lg[y-x+1];
        return getmin(f[ln][x],f[ln][y-(1<<ln)+1]);
    }
    inline int getdis(int x,int y){
        if(x==0 || y==0) return 0;
        return s[x]+s[y]-2*s[getlca(x,y)];
    }
    inline void init(){
        dfs(1,0);
        if(n==500000) cout<<idx<<endl;
        lg[0]=-1;fr(i,1,idx) lg[i]=lg[i/2]+1;
        fr(j,1,lg[idx]) fr(i,1,idx){
            if(i+(1<<j)-1>idx) break;
            f[j][i]=getmin(f[j-1][i],f[j-1][i+(1<<(j-1))]);
        }
    }
}
int ans[Maxn];
int vis[Maxn];
int now;
inline int getmex(){while(vis[now]) ++now;return now;}
struct point{int val,id;}p[Maxn];
inline bool cmp(point a,point b){return a.val<b.val;}
inline void init(){
    n=read();q=read();
    fr(i,1,n) p[i].val=read(),p[i].id=i;
    fr(i,1,n-1){
        int x,y,z;
        x=read();y=read();z=read();
        add(x,y,z);add(y,x,z);
    }LCA::init();
    sort(p+1,p+n+1,cmp);
}
struct line{int id1,id2;}pr[Maxn];
bool operator < (line A,line B){return LCA::getdis(A.id1,A.id2)<LCA::getdis(B.id1,B.id2);}
inline bool check(int x,int id,int k){
    return LCA::getdis(x,pr[id].id1)<=k && LCA::getdis(x,pr[id].id2)<=k;
}
inline void work(){
    fr(i,1,n) vis[p[i].val]=1,ans[i]=getmex();
    // fr(i,)
    fr(i,1,n) pr[i].id1=p[i].id;
    fr(i,2,n){
        pr[i]=pr[i-1];
        line now=(line){pr[i].id1,p[i].id};
        if(pr[i]<now) pr[i]=now;
        now=(line){pr[i].id2,p[i].id};
        if(pr[i]<now) pr[i]=now;
    }
    while(q--){
        int x,k;
        x=read();k=read();
        int l=1,r=n,answer=0;
        while(l<=r){
            int mid;mid=(l+r)>>1;
            if(check(x,mid,k)) answer=mid,l=mid+1;
            else r=mid-1;
        }writeln(ans[answer]);
    }
}
signed main(){
	// freopen("input.in","r",stdin);
	// freopen("output.out","w",stdout);
    init();work();
    // printf("\nTIME:%.3lf",(double)clock()/CLOCKS_PER_SEC);
	return 0;
}