#include <bits/stdc++.h>
using namespace std;
#define LL long long
#define ULL unsigned long long
#define Enter putchar('\n')
#define spc putchar(' ')
#define pb push_back
#define fi first
#define se second
inline void read(int &num){num=0;int f=1;char ch=getchar();while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){num=(num<<1)+(num<<3)+(ch^48);ch=getchar();}num*=f;}
inline void lread(long long &num){num=0;int f=1;char ch=getchar();while(ch>'9'||ch<'0'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){num=(num<<1)+(num<<3)+(ch^48);ch=getchar();}num*=f;}
void print(long long num){if(num<0){putchar('-');num=-num;}if(num>9){print(num/10);}putchar((num%10)^48);}
const int N=5e5+9;
int a[N],id[N],cnt,fi[N],st[N<<1][20],lg[N<<1],dm[N][2],vi[N<<1];
struct node{
    int v;
    LL w;
};
LL dp[N];
vector<node> g[N];
bool cmp(const int &x,const int &y){
    return a[x]<a[y];
}
void dfs(int u,int fr){
    fi[u]=++cnt;
    st[cnt][0]=cnt;
    vi[cnt]=u;
    for(int i=0;i<g[u].size();i++){
        if(g[u][i].v==fr)continue;
        dp[g[u][i].v]=dp[u]+g[u][i].w;
        dfs(g[u][i].v,u);
        st[++cnt][0]=fi[u];
        vi[cnt]=u;
    }
}
int ask1(int x,int y){
    if(!x||!y)return 0;
    if(fi[x]>fi[y])swap(x,y);
    int z=lg[fi[y]-fi[x]+1];
    if(a[1]==416779)cout<<fi[y]<<' '<<fi[x]<<' '<<z<<':';
    z=min(st[fi[x]][z],st[fi[y]-(1<<z)+1][z]);
    if(a[1]==416779)cout<<z<<'#'<<dp[x]+dp[y]-dp[vi[z]]-dp[vi[z]];
    return dp[x]+dp[y]-dp[vi[z]]-dp[vi[z]];
}
int ask(int x,int y){
    if(!x||!y)return 0;
    if(fi[x]>fi[y])swap(x,y);
    int z=lg[fi[y]-fi[x]+1];
    z=min(st[fi[x]][z],st[fi[y]-(1<<z)+1][z]);
    return dp[x]+dp[y]-dp[vi[z]]-dp[vi[z]];
}
int main(){
    int n,Q,x,y,z,mx=0;
    LL s;
    read(n),read(Q);
    for(int i=1;i<=n;i++)read(a[i]),id[i]=i;
    sort(id+1,id+n+1,cmp);
    for(int i=1;i<=n;i++){
        if(a[id[i]]==mx)++mx;
        else break;
    }
    for(int i=1;i<n;i++){
        read(x),read(y),read(z);
        g[x].pb({y,z});
        g[y].pb({x,z});
    }
    dfs(1,0);
    for(int i=1,j=1;i<=19;i++,j<<=1){
        for(int k=1;k+j+j<=n+n;k++){
            st[k][i]=min(st[k][i-1],st[k+j][i-1]);
        }
    }
    for(int i=2;i<=1e6;i++)lg[i]=lg[i>>1]+1;
    dm[2][0]=dm[1][0]=id[1];
    dm[2][1]=id[2];
    for(int i=3;i<=mx;i++){
        x=ask(dm[i-1][0],dm[i-1][1]);
        y=ask(dm[i-1][0],id[i]);
        z=ask(dm[i-1][1],id[i]);
        if(x>=y&&x>=z){
            dm[i][0]=dm[i-1][0],dm[i][1]=dm[i-1][1];
            continue;
        }
        if(y>z){
            dm[i][0]=dm[i-1][0],dm[i][1]=id[i];
        }
        else{
            dm[i][1]=dm[i-1][1],dm[i][0]=id[i];
        }
    }
    while(Q--){
        read(x),lread(s);
        if(a[1]==416779){
            ask1(x,id[1]);
            cout<<endl;
        }
        int l=0,r=mx,mid;
        while(l<r){
            mid=(l+r+1)>>1;
            if(max(ask(x,dm[mid][0]),ask(x,dm[mid][1]))<=s){
                l=mid;
            }
            else r=mid-1;
        }
        print(l),Enter;
    }
    return 0;
}