#include <bits/stdc++.h>
//#include<ext/pb_ds/assoc_container.hpp>
//#include<ext/pb_ds/hash_policy.hpp>
//using namespace __gnu_pbds;
using std::max; using std::min; using std::pair;
long long scan() {
  long long x = 0; char ch = getchar();
  for (; !isdigit(ch); ch = getchar());
  for (; isdigit(ch); ch = getchar()) x = 10 * x + ch - '0';
  return x;
}
int top, stk[11];
void print(int x) {
  do stk[++top] = x % 10, x /= 10; while (x);
  while (top) putchar(stk[top--] + '0');
}
const int N = 5e5 + 5;
int n, Q, id[N], ansmx,
    tot, head[N], nxt[2 * N], ver[2 * N], wei[2 * N],
    Fa[N], fullSz, sz[N], msz[N];
bool idv[N], vis[N];
std::vector<int> vec, arr[N];
std::vector<pair<int, int>> res[N];
std::map<int, int> dir[N];
std::map<int, long long> dis[N];
void addEdge(int u, int v, int w) {
  nxt[++tot] = head[u], head[u] = tot, ver[tot] = v, wei[tot] = w;
}
void prepare(int u, int fa) {
  ++fullSz, sz[u] = 1, msz[u] = 0, vec.emplace_back(u);
  for (int i = head[u]; i; i = nxt[i]) {
    int v = ver[i]; if (vis[v] || v == fa) continue;
    prepare(v, u), sz[u] += sz[v], msz[u] = max(msz[u], sz[v]);
  }
}
void dfs(int u, int fa, long long d, int rot) {
  dis[rot][u] = d;
  for (int i = head[u]; i; i = nxt[i]) {
    int v = ver[i]; if (vis[v] || v == fa) continue;
    dfs(v, u, d + wei[i], rot);
  }
}
void construct(int divFa) {
  int rot = 0;
  for (int v: vec) {
    msz[v] = max(msz[v], fullSz - sz[v]);
    if (!rot || msz[v] < msz[rot]) rot = v;
  }
  dfs(rot, 0, 0, rot);
  std::sort(vec.begin(), vec.end(),
    [&](int x, int y) { return dis[rot][x] < dis[rot][y]; });
  vis[rot] = true, Fa[rot] = divFa, arr[rot] = vec;
  for (int i = head[rot]; i; i = nxt[i]) {
    int u = ver[i]; if (vis[u]) continue;
    fullSz = 0, vec.clear(), prepare(u, 0);
    for (int v: vec) dir[rot][v] = u;
    construct(rot);
  }
  int sz = arr[rot].size(); res[rot].resize(sz);
  int mn = 0, cmn = 0;
  for (int i = sz - 1; i >= 0; --i) {
    int v = arr[rot][i];
    if (!mn) mn = v;
    else {
      if (dir[rot][mn] == dir[rot][v]) {
        if (id[v] < id[mn]) mn = v;
      }
      else if (dir[rot][cmn] == dir[rot][v]) {
        if (id[v] < id[cmn]) cmn = v;
      }
      else {
        if (id[v] < id[mn]) cmn = mn, mn = v;
        else if (id[v] < id[cmn]) cmn = v;
      }
      if (id[mn] > id[cmn]) std::swap(mn, cmn);
    }
    res[rot][i] = {mn, cmn};
  }
}
int main() {
  n = scan(), Q = scan();
  id[0] = INT_MAX;
  for (int i = 1; i <= n; ++i) {
    id[i] = scan(); if (id[i] < N) idv[id[i]] = true;
  }
  for (int i = 0; i < N; ++i) if (!idv[i]) { ansmx = i; break; }
  for (int i = 1; i < n; ++i) {
    int u = scan(), v = scan(), w = scan();
    addEdge(u, v, w), addEdge(v, u, w);
  }
  prepare(1, 0), construct(0);
  while (Q--) {
    int ask = scan(), ans = ansmx; long long d = scan();
    for (int u = ask; u; u = Fa[u]) {
	    int sz = arr[u].size(), l = 0, r = sz;
	    long long k = d - dis[u][ask];
	    while (l < r) {
	      int mid = (l + r) >> 1;
	      if (dis[u][arr[u][mid]] <= k) l = mid + 1;
	      else r = mid;
      }
      if (l < sz) {
        pair<int, int> it = res[u][l];
        if (dir[u][it.first] == dir[u][ask]) ans = min(ans, id[it.second]);
        else ans = min(ans, id[it.first]);
      }
    }
    print(ans), putchar('\n');
  }
  return 0;
}