#include<bits/stdc++.h>

using namespace std;

template< class Monoid, class OperatorMonoid = Monoid >
struct RandomizedBinarySearchTree
{
  using F = function< Monoid(Monoid, Monoid) >;
  using G = function< Monoid(Monoid, OperatorMonoid) >;
  using H = function< OperatorMonoid(OperatorMonoid, OperatorMonoid) >;
  using P = function< OperatorMonoid(OperatorMonoid, int) >;

  inline int xor128()
  {
    static int x = 123456789;
    static int y = 362436069;
    static int z = 521288629;
    static int w = 88675123;
    int t;

    t = x ^ (x << 11);
    x = y;
    y = z;
    z = w;
    return w = (w ^ (w >> 19)) ^ (t ^ (t >> 8));
  }

  struct Node
  {
    Node *l, *r;
    int cnt;
    Monoid key, sum;
    OperatorMonoid lazy;

    Node() {}

    Node(const Monoid &k, const OperatorMonoid &p) : cnt(1), key(k), sum(k), lazy(p), l(nullptr), r(nullptr) {}
  };

  vector< Node > pool;
  int ptr;

  const Monoid M1;
  const OperatorMonoid OM0;
  const F f;
  const G g;
  const H h;
  const P p;

  RandomizedBinarySearchTree(int sz, const F &f, const Monoid &M1) :
      pool(sz), ptr(0), f(f), g(G()), h(H()), p(P()), M1(M1), OM0(OperatorMonoid()) {}

  RandomizedBinarySearchTree(int sz, const F &f, const G &g, const H &h, const P &p,
                             const Monoid &M1, const OperatorMonoid &OM0) :
      pool(sz), ptr(0), f(f), g(g), h(h), p(p), M1(M1), OM0(OM0) {}

  inline Node *alloc(const Monoid &key) { return &(pool[ptr++] = Node(key, OM0)); }

  virtual Node *clone(Node *t) { return t; }

  inline int count(const Node *t) { return t ? t->cnt : 0; }

  inline Monoid sum(const Node *t) { return t ? t->sum : M1; }

  inline Node *update(Node *t)
  {
    t->cnt = count(t->l) + count(t->r) + 1;
    t->sum = f(f(sum(t->l), sum(t->r)), t->key);
    return t;
  }

  Node *propagete(Node *t)
  {
    t = clone(t);
    if(t->lazy != OM0) {
      t->key = g(t->key, t->lazy);
      if(t->l) {
        t->l = clone(t->l);
        t->l->lazy = h(t->l->lazy, t->lazy);
        t->l->sum = f(t->l->sum, p(t->lazy, count(t->l)));
      }
      if(t->r) {
        t->r = clone(t->r);
        t->r->lazy = h(t->r->lazy, t->lazy);
        t->r->sum = f(t->r->sum, p(t->lazy, count(t->r)));
      }
      t->lazy = OM0;
    }
    return update(t);
  }

  Node *merge(Node *l, Node *r)
  {
    if(!l || !r) return l ? l : r;
    if(xor128() % (l->cnt + r->cnt) < l->cnt) {
      l = propagete(l);
      l->r = merge(l->r, r);
      return update(l);
    } else {
      r = propagete(r);
      r->l = merge(l, r->l);
      return update(r);
    }
  }

  pair< Node *, Node * > split(Node *t, int k)
  {
    if(!t) return {t, t};
    t = propagete(t);
    if(k <= count(t->l)) {
      auto s = split(t->l, k);
      t->l = s.second;
      return {s.first, update(t)};
    } else {
      auto s = split(t->r, k - count(t->l) - 1);
      t->r = s.first;
      return {update(t), s.second};
    }
  }

  Node *build(int l, int r, const vector< Monoid > &v)
  {
    if(l + 1 >= r) return alloc(v[l]);
    return merge(build(l, (l + r) >> 1, v), build((l + r) >> 1, r, v));
  }

  Node *build(const vector< Monoid > &v)
  {
    ptr = 0;
    return build(0, (int) v.size(), v);
  }

  void dump(Node *r, typename vector< Monoid >::iterator &it)
  {
    if(!r) return;
    r = propagete(r);
    dump(r->l, it);
    *it = r->key;
    dump(r->r, ++it);
  }

  vector< Monoid > dump(Node *r)
  {
    vector< Monoid > v((size_t) count(r));
    auto it = begin(v);
    dump(r, it);
    return v;
  }

  string to_string(Node *r)
  {
    auto s = dump(r);
    string ret;
    for(int i = 0; i < s.size(); i++) ret += ", ";
    return (ret);
  }

  void insert(Node *&t, int k, const Monoid &v)
  {
    auto x = split(t, k);
    t = merge(merge(x.first, alloc(v)), x.second);
  }

  void erase(Node *&t, int k)
  {
    auto x = split(t, k);
    t = merge(x.first, split(x.second, 1).second);
  }

  Monoid query(Node *&t, int a, int b)
  {
    auto x = split(t, a);
    auto y = split(x.second, b - a);
    auto ret = sum(y.first);
    t = merge(x.first, merge(y.first, y.second));
    return ret;
  }

  void set_propagate(Node *&t, int a, int b, const OperatorMonoid &p)
  {
    auto x = split(t, a);
    auto y = split(x.second, b - a);
    y.first->lazy = h(y.first->lazy, p);
    t = merge(x.first, merge(propagete(y.first), y.second));
  }

  void set_element(Node *&t, int k, const Monoid &x)
  {
    t = propagete(t);
    if(k < count(t->l)) set_element(t->l, k, x);
    else if(k == count(t->l)) t->key = t->sum = x;
    else set_element(t->r, k - count(t->l) - 1, x);
    t = update(t);
  }


  int size(Node *t)
  {
    return count(t);
  }

  bool empty(Node *t)
  {
    return !t;
  }

  Node *makeset()
  {
    return (nullptr);
  }
};

template< class Monoid, class OperatorMonoid = Monoid >
struct PresidentRandomizedBinarySearchTree : RandomizedBinarySearchTree< Monoid, OperatorMonoid >
{
  using RBST = RandomizedBinarySearchTree< Monoid, OperatorMonoid >;
  using Node = typename RBST::Node;
  using F = typename RBST::F;
  using G = typename RBST::G;
  using H = typename RBST::H;
  using P = typename RBST::P;

  PresidentRandomizedBinarySearchTree(int sz, const F &f, const Monoid &M1) :
      RBST(sz, f, M1) {}

  PresidentRandomizedBinarySearchTree(int sz, const F &f, const G &g, const H &h, const P &p,
                                      const Monoid &M1, const OperatorMonoid &OM0) :
      RBST(sz, f, g, h, p, M1, OM0) {}

  Node *clone(Node *t) override { return &(RBST::pool[RBST::ptr++] = *t); }

  Node *rebuild(Node *r) { return RBST::build(RBST::dump(r)); }
};

template< class T >
struct OrderedMultiSet : PresidentRandomizedBinarySearchTree< T >
{
  using RBST = PresidentRandomizedBinarySearchTree< T >;
  using Node = typename RBST::Node;

  OrderedMultiSet(int sz) : RBST(sz, [&](T x, T y) { return x; }, T()) {}

  T kth_element(Node *t, int k)
  {
    if(k < RBST::count(t->l)) return kth_element(t->l, k);
    if(k == RBST::count(t->l)) return t->key;
    return kth_element(t->r, k - RBST::count(t->l) - 1);
  }

  virtual void insert_key(Node *&t, const T &x)
  {
    RBST::insert(t, lower_bound(t, x), x);
  }

  void erase_key(Node *&t, const T &x)
  {
    if(!count(t, x)) return;
    RBST::erase(t, lower_bound(t, x));
  }

  int count(Node *t, const T &x)
  {
    return upper_bound(t, x) - lower_bound(t, x);
  }

  int lower_bound(Node *t, const T &x)
  {
    if(!t) return 0;
    if(x <= t->key) return lower_bound(t->l, x);
    return lower_bound(t->r, x) + RBST::count(t->l) + 1;
  }

  int upper_bound(Node *t, const T &x)
  {
    if(!t) return 0;
    if(x < t->key) return upper_bound(t->l, x);
    return upper_bound(t->r, x) + RBST::count(t->l) + 1;
  }
};

struct CentroidPathDecomposition
{
  struct Centroid
  {
    int ParIndex, ParDepth, Deep;
    vector< int > node;

    Centroid(int idx, int dep, int deep) : ParIndex(idx), ParDepth(dep), Deep(deep) {}

    inline size_t size()
    {
      return (node.size());
    }

    inline int &operator[](int k)
    {
      return (node[k]);
    }

    inline pair< int, int > Up()
    {
      return (make_pair(ParIndex, ParDepth));
    }
  };

  vector< vector< int > > graph;
  vector< int > SubTreeSize, NextPath;
  vector< int > TreeIndex, TreeDepth;
  vector< Centroid > Centroids;

  void BuildSubTreeSize()
  {
    stack< pair< int, int > > s;
    s.emplace(0, -1);
    while(!s.empty()) {
      auto p = s.top();
      s.pop();
      if(~SubTreeSize[p.first]) {
        NextPath[p.first] = -1;
        for(auto &to : graph[p.first]) {
          if(p.second == to) continue;
          SubTreeSize[p.first] += SubTreeSize[to];
          if(NextPath[p.first] == -1 || SubTreeSize[NextPath[p.first]] < SubTreeSize[to]) {
            NextPath[p.first] = to;
          }
        }
      } else {
        s.push(p);
        SubTreeSize[p.first] = 1;
        for(auto &to : graph[p.first]) {
          if(p.second != to) s.emplace(to, p.first);
        }
      }
    }
  }

  void BuildPath()
  {
    stack< pair< int, int > > s;
    Centroids.emplace_back(-1, -1, 0);
    s.emplace(0, -1);
    TreeIndex[0] = 0;
    while(!s.empty()) {
      auto p = s.top();
      s.pop();
      TreeDepth[p.first] = (int) Centroids[TreeIndex[p.first]].size();
      for(auto &to : graph[p.first]) {
        if(p.second == to) continue;
        if(to == NextPath[p.first]) { // Centroid-Path
          TreeIndex[to] = TreeIndex[p.first];
        } else {                  // Not Centroid-Path
          TreeIndex[to] = (int) Centroids.size();
          Centroids.emplace_back(TreeIndex[p.first], TreeDepth[p.first], Centroids[TreeIndex[p.first]].Deep + 1);
        }
        s.emplace(to, p.first);
      }
      Centroids[TreeIndex[p.first]].node.emplace_back(p.first);
    }
  }

  void AddEdge(int x, int y)
  {
    graph[x].push_back(y);
    graph[y].push_back(x);
  }

  virtual void Build()
  {
    BuildSubTreeSize();
    BuildPath();
  }

  inline size_t size()
  {
    return (Centroids.size());
  }

  inline pair< int, int > Information(int idx)
  {
    return (make_pair(TreeIndex[idx], TreeDepth[idx]));
  }

  inline Centroid &operator[](int k)
  {
    return (Centroids[k]);
  }

  inline int LCA(int a, int b)
  {
    int TreeIdxA, TreeDepthA, TreeIdxB, TreeDepthB;
    tie(TreeIdxA, TreeDepthA) = Information(a);
    tie(TreeIdxB, TreeDepthB) = Information(b);
    while(TreeIdxA != TreeIdxB) {
      if(Centroids[TreeIdxA].Deep > Centroids[TreeIdxB].Deep) {
        tie(TreeIdxA, TreeDepthA) = Centroids[TreeIdxA].Up();
      } else {
        tie(TreeIdxB, TreeDepthB) = Centroids[TreeIdxB].Up();
      }
    }
    if(TreeDepthA > TreeDepthB) swap(TreeDepthA, TreeDepthB);
    return (Centroids[TreeIdxA][TreeDepthA]);
  }

  inline virtual void query(int a, int b, const function< void(int, int, int) > &f)
  {
    int TreeIdxA, TreeDepthA, TreeIdxB, TreeDepthB;
    tie(TreeIdxA, TreeDepthA) = Information(a);
    tie(TreeIdxB, TreeDepthB) = Information(b);
    while(TreeIdxA != TreeIdxB) {
      if(Centroids[TreeIdxA].Deep > Centroids[TreeIdxB].Deep) {
        f(TreeIdxA, 0, TreeDepthA + 1);
        tie(TreeIdxA, TreeDepthA) = Centroids[TreeIdxA].Up();
      } else {
        f(TreeIdxB, 0, TreeDepthB + 1);
        tie(TreeIdxB, TreeDepthB) = Centroids[TreeIdxB].Up();
      }
    }
    if(TreeDepthA > TreeDepthB) swap(TreeDepthA, TreeDepthB);
    f(TreeIdxA, TreeDepthA, TreeDepthB + 1);
  }

  CentroidPathDecomposition(int SZ)
  {
    graph.resize(SZ);
    SubTreeSize.assign(SZ, -1);
    NextPath.resize(SZ);
    TreeIndex.resize(SZ);
    TreeDepth.resize(SZ);
  }
};

OrderedMultiSet< int > tree(5000000);
OrderedMultiSet< int >::Node *nodes[100000];

int N, Q, X[100000];
vector< int > g[100000];
int parent[100000];

void dfs(int idx, int par, OrderedMultiSet< int >::Node *par_set)
{
  parent[idx] = par;
  tree.insert_key(par_set, X[idx]);
  nodes[idx] = par_set;
  for(auto &to : g[idx]) if(to != par) dfs(to, idx, par_set);
}

int main()
{
  scanf("%d %d", &N, &Q);
  CentroidPathDecomposition gg(N);
  vector< int > vs;
  for(int i = 0; i < N; i++) {
    scanf("%d", &X[i]);
    vs.emplace_back(X[i]);
  }
  sort(begin(vs), end(vs));
  vs.erase(unique(begin(vs), end(vs)), end(vs));
  for(int i = 1; i < N; i++) {
    int x, y;
    scanf("%d %d", &x, &y);
    --x, --y;
    g[x].emplace_back(y);
    g[y].emplace_back(x);
    gg.AddEdge(x, y);
  }
  dfs(0, -1, tree.makeset());
  gg.Build();

  for(int i = 0; i < Q; i++) {
    int x, y, z;
    scanf("%d %d %d", &x, &y, &z);
    --x, --y;
    int lca = gg.LCA(x, y);
    int ng = -1, ok = (int) vs.size() - 1;
    auto sum = [&](int v)
    {
      int ret = 0;
      ret += tree.upper_bound(nodes[x], vs[v]);
      ret += tree.upper_bound(nodes[y], vs[v]);
      ret -= tree.upper_bound(nodes[lca], vs[v]);
      if(lca) ret -= tree.upper_bound(nodes[parent[lca]], vs[v]);
      return ret;
    };
    while(ok - ng > 1) {
      int mid = (ok + ng) >> 1;
      if(sum(mid) >= z) ok = mid;
      else ng = mid;
    }
    printf("%d\n", vs[ok]);
  }
}



Measured memory_bytes: 209552