#include<iostream>
#include<cstring>
#include<vector>
#include<algorithm>
using namespace std;
using LL = long long;
const int maxn = 5e5 + 5, INF = 1e9;
vector<pair<int, int> > g[maxn];
bool v[maxn];
int ans[maxn], a[maxn];
vector<pair<LL, int> > que[maxn];

int get_size(int u, int fa){
    if (v[u]) return 0;
    int sz = 1;
    for(auto [j, w] : g[u]){
        if (j == fa) continue;
        sz += get_size(j, u);
    }
    return sz;
}

int get_wc(int u, int fa, int tot, int &wc){
    if (v[u]) return 0;
    int mx = 0, sum = 1;
    for(auto [j, w] : g[u]){
        if (j == fa) continue;
        int t = get_wc(j, u, tot, wc);
        mx = max(mx, t);
        sum += t;
    }
    mx = max(mx, tot - sum);
    if (mx <= tot / 2) wc = u;
    return sum;
}

void dfs(int u, int fa, int dist, vector<pair<LL, int> > &p){
    if (v[u]) return;
    p.push_back({dist, u});
    for(auto [j, w] : g[u]){
        if (j == fa) continue;
        dfs(j, u, dist + w, p);
    }
}

int tr[maxn * 4];

void build(int u, int l, int r, vector<pair<LL, int> > &init){
    if (l == r){
        tr[u] = a[init[r].second];
        return;
    }
    int mid = (l + r) / 2;
    build(2 * u, l, mid, init);
    build(2 * u + 1, mid + 1, r, init);
    tr[u] = min(tr[2 * u], tr[2 * u + 1]);
}

void modify(int u, int l, int r, int x, int v){
    if (l == r){
        tr[u] = v;
        return;
    }
    int mid = (l + r) / 2;
    if (x <= mid) modify(2 * u, l, mid, x, v);
    else modify(2 * u + 1, mid + 1, r, x, v);
    tr[u] = min(tr[2 * u], tr[2 * u + 1]);
}

int query(int u, int l, int r, int L, int R){
    if (l > R || r < L) return INF;
    if (l >= L && r <= R) return tr[u];
    int mid = (l + r) / 2;
    return min(query(2 * u, l, mid, L, R), query(2 * u + 1, mid + 1, r, L, R));
}

int id[maxn];

void calc(int u){
    if (v[u]) return;
    get_wc(u, -1, get_size(u, -1), u);
    
    vector<pair<LL, int> > p;
    dfs(u, -1, 0, p);
    sort(p.begin(), p.end());
    for(int i = 0; i < p.size(); i++){
        id[p[i].second] = i;
    }
    const int m = p.size();

    auto get = [&](LL x){
        return int(lower_bound(p.begin(), p.end(), make_pair(x + 1, 0)) - p.begin());
    };

    build(1, 0, m - 1, p);
    
    for(auto [d, id] : que[u]){
        ans[id] = min(ans[id], query(1, 0, m - 1, get(d), m - 1));
    }
    
    for(auto [j, w] : g[u]){
        if (v[j]) continue;
        vector<pair<LL, int> > q;
        dfs(j, u, w, q);
        for(auto [dist, x] : q){
            modify(1, 0, m - 1, id[x], INF);
        }
        for(auto [dist, x] : q){
            for(auto [d, id] : que[x]){
                ans[id] = min(ans[id], query(1, 0, m - 1, get(d - dist), m - 1));
            }
        }
        for(auto [dist, x] : q){
            modify(1, 0, m - 1, id[x], a[x]);
        }
    }
    v[u] = true;
    for(auto [j, w] : g[u]){
        calc(j);
    }
}

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);

    int n, q;
    cin >> n >> q;
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        v[a[i]] = true;
    }
    for(int i = 0; i < n - 1; i++){
        int a, b, c;
        cin >> a >> b >> c;
        g[a].push_back({b, c});
        g[b].push_back({a, c});
    }
    int mex = 0;
    while(v[mex]) mex++;
    memset(v, 0, sizeof v);
    for(int i = 0; i < q; i++){
        int x; LL k;
        cin >> x >> k;
        ans[i] = mex;
        que[x].push_back({k, i});
    }
    calc(1);
    for(int i = 0; i < q; i++){
        cout << ans[i] << '\n';
    }

}