#include <bits/stdc++.h>
#pragma GCC optimize("O3")
using namespace std;
#define ll long long
#define fr first
#define sc second
#define pb push_back
#define MAX ((ll)(1e18 + 100))
#define MX ((ll)(5e5 + 100))
#define ARRS ((ll)(1e6 + 100))
#define MOD ((ll)(1e9 + 7))
#define PI ((double)3.141592653)
#define EP ((double)(1e-9))
#define LG 21

ll w[ARRS];
ll sz[ARRS];
ll f[ARRS];
vector<pair<ll, ll>> v[ARRS];
pair<ll, ll> cpr[ARRS];

ll fc(ll x, ll pr, ll n) {
  sz[x] = 1;
  ll ok = 1;
  ll ans = -1;
  for (auto y : v[x]) {
    if (f[y.fr] || y.fr == pr)
      continue;
    ans = max(ans, fc(y.fr, x, n));
    ok &= sz[y.fr] <= (n / 2);
    sz[x] += sz[y.fr];
  }
  ok &= (n - sz[x]) <= (n / 2);
  if (ok)
    return x;
  else
    return ans;
}

ll CS;
multiset<pair<ll, pair<ll, ll>>> ms;
void go(ll x, ll pr, ll d) {

  ms.insert({d, {w[x], CS}});

  sz[x] = 1;
  for (auto y : v[x]) {
    if (f[y.fr] || y.fr == pr)
      continue;
    go(y.fr, x, d + y.sc);
    sz[x] += sz[y.fr];
  }
}

vector<pair<ll, ll>> upd(vector<pair<ll, ll>> mns, pair<ll, ll> nw) {
  mns.pb(nw);
  sort(mns.begin(), mns.end());
  if (mns[0].sc == mns[1].sc) {
    return {mns[0], mns[2]};
  } else {
    return {mns[0], mns[1]};
  }
}

map<ll, vector<pair<ll, ll>>> rmin[ARRS];

ll dist(ll x, ll pr, ll tgt) {
  if (x == tgt)
    return 0;
  for (auto y : v[x]) {
    if (f[y.fr] || y.fr == pr)
      continue;
    ll d = dist(y.fr, x, tgt);
    if (d != -1) {
      return d + y.sc;
    }
  }
  return -1;
}

ll buildTree(ll somerandomx, ll n) {
  auto C = fc(somerandomx, -1, n);

  vector<pair<ll, pair<ll, ll>>> subs;
  CS = 0;
  for (auto y : v[C]) {
    if (f[y.fr])
      continue;
    CS++;
    go(y.fr, C, y.sc);
    subs.pb({y.fr, {sz[y.fr], y.sc}});
  }
  ms.insert({{-1, {w[C], -5}}});
  // cout << "--------- " << C << " ------------" << endl;
  vector<pair<ll, ll>> v = {{MAX, -1}, {MAX + 1, -2}};
  for (auto it = ms.rbegin(); it != ms.rend(); it++) {
    auto cur = *it;
    v = upd(v, cur.sc);
    rmin[C][cur.fr] = v;
  }
  // for (auto x : rmin[C]) {
  //   cout << x.fr << ":" << endl;
  //   for (auto mn : x.sc) {
  //     cout << mn.fr << ", " << mn.sc << endl;
  //   }
  // }
  // cout << "---------" << endl;

  f[C] = 1;
  for (auto sub : subs) {
    ll Cc = buildTree(sub.fr, sub.sc.fr);
    ll dst = dist(sub.fr, C, Cc) + sub.sc.sc;
    cpr[Cc] = {C, dst};
    // cout << C << " -> " << Cc << " ; " << dst << endl;
  }
  return C;
}

int main() {

  ios::sync_with_stdio(0);
  ll n, q;
  cin >> n >> q;
  vector<ll> tv;
  for (int i = 0; i < n; i++) {
    cin >> w[i];
    tv.pb(w[i]);
  }
  sort(tv.begin(), tv.end());
  ll mex = n;
  for (int i = 0; i < n; i++) {
    if (i != tv[i]) {
      mex = i;
      break;
    }
  }
  // cout << mex << endl;

  for (int i = 0; i < n - 1; i++) {
    ll k, p, l;
    cin >> k >> p >> l;
    k--;
    p--;
    v[k].pb({p, l});
    v[p].pb({k, l});
  }
  // cout << n << endl;
  ll C = buildTree(0, n);
  cpr[C] = {-1, -1};
// cout<<"**********"<<endl;

  while (q--) {
    ll x, r;
    cin >> x >> r;
    x--;
    ll ans = mex;
    ll lasts = -100;
    while (x != -1) {
      auto cs = (*rmin[x].lower_bound(r)).sc;
      auto cans = cs[0].fr;
      // cout << x << " " << r << endl;
      // cout << cans << endl;
      if (cs[0].sc == lasts)
        cans = cs[1].fr;
      // cout << cans << endl;
      // cout << endl;
      ans = min(ans, cans);
      r -= cpr[x].fr;
      x = cpr[x].fr;
    }
    cout << ans << endl;
    // cout << "--" << endl;
  }

  return 0;
}