#include <bits/stdc++.h>
using namespace std;
static constexpr int Maxn = 5e5 + 5;
static constexpr int LogN = 20;
int n, qn, ans[Maxn], mans;
int a[Maxn], ia[Maxn];
vector<pair<int, int64_t>> g[Maxn];
vector<pair<int64_t, int>> q[Maxn];
vector<tuple<int64_t, int, int>> cq[Maxn];
namespace ndt {
  int anc[Maxn], layer[Maxn];
  int64_t cdep[LogN][Maxn];
#define foreach(u, v, w)                                      \
  for (const auto &[v, w]: g[u]) if (v != fa && !visited[v])
  bool visited[Maxn]; int totN, mnN, root, siz[Maxn];
  vector<int> all[LogN];
  int calcsz(int u, int fa) { int r = 1; foreach(u, v, w) r += calcsz(v, u); return r; }
  void rooting(int u, int fa) {
    int mx = 0; siz[u] = 1;
    foreach(u, v, w) rooting(v, u), siz[u] += siz[v], mx = max(mx, siz[v]);
    if ((mx = max(mx, totN - siz[u])) < mnN) mnN = mx, root = u;
  } // ndt::rooting
  int get_root(int u) { mnN = totN = calcsz(u, 0), root = 0; return rooting(u, 0), root; }
  void subtree(int u, int fa, int64_t depth, int layer) {
    cdep[layer][u] = depth; all[layer].push_back(u);
    foreach(u, v, w) subtree(v, u, depth + w, layer);
  } // ndt::subtree
  void divide(int u, int fa = 0, int lay = 1) {
    visited[u] = true, anc[u] = fa, subtree(u, 0, 0, layer[u] = lay);
    foreach(u, v, w) divide(get_root(v), u, lay + 1);
  } // ndt::divide
  void build(void) { divide(get_root(1)); }
} // namespace ndt
void upgrade_query(int u) {
  using namespace ndt;
  for (int x = u; x; x = anc[x])
    for (const auto &[tw, ti]: q[u]) cq[x].emplace_back(tw, u, ti);
} // upgrade_query
void update(int u) {
  using namespace ndt;
  for (int x = u; x; x = anc[x]) {
    int lay = layer[x]; int64_t wd = cdep[lay][u];
    while (!cq[x].empty()) {
      auto [w, v, i] = cq[x].back();
      if (ans[i] != -1) { cq[x].pop_back(); continue; }
      if (wd + cdep[lay][v] > w) { ans[i] = a[u]; cq[x].pop_back(); continue; }
      else break;
    }
  }
} // update
int main(void) {
  cin.tie(nullptr)->sync_with_stdio(false);
  cin >> n >> qn; memset(ia, -1, sizeof(ia));
  memset(ans, -1, sizeof(ans));
  for (int i = 1; i <= n; ++i) cin >> a[i];
  for (int i = 1; i <= n; ++i) if (a[i] <= n) ia[a[i]] = i;
  for (mans = 0; ia[mans] != -1; ++mans);
  auto add_edge = [&](int u, int v, int64_t w)->void {
    g[u].emplace_back(v, w);
    g[v].emplace_back(u, w);
  }; // main::add_edge
  for (int i = 1, u, v, w; i < n; ++i)
    cin >> u >> v >> w, add_edge(u, v, w);
  for (int i = 1, u; i <= qn; ++i) {
    int64_t w; cin >> u >> w, q[u].emplace_back(w, i);
  } ndt::build();
  for (int i = 1; i <= n; ++i) upgrade_query(i);
  for (int i = 1; i <= n; ++i) sort(cq[i].rbegin(), cq[i].rend());
  for (int c = 0; c < mans; ++c) update(ia[c]);
  for (int i = 1; i <= qn; ++i)
    if (ans[i] == -1) ans[i] = mans;
  for (int i = 1; i <= qn; ++i) printf("%d\n", ans[i]);
  return 0;
} // main