#include <bits/stdc++.h>

using namespace std;

using int64 = long long;
const int mod = 998244353;

const int64 infll = (1LL << 60) - 1;
const int inf = (1 << 30) - 1;

struct IoSetup {
  IoSetup() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);
    cerr << fixed << setprecision(10);
  }
} iosetup;


template< typename T1, typename T2 >
ostream &operator<<(ostream &os, const pair< T1, T2 > &p) {
  os << p.first << " " << p.second;
  return os;
}

template< typename T1, typename T2 >
istream &operator>>(istream &is, pair< T1, T2 > &p) {
  is >> p.first >> p.second;
  return is;
}

template< typename T >
ostream &operator<<(ostream &os, const vector< T > &v) {
  for(int i = 0; i < (int) v.size(); i++) {
    os << v[i] << (i + 1 != v.size() ? " " : "");
  }
  return os;
}

template< typename T >
istream &operator>>(istream &is, vector< T > &v) {
  for(T &in : v) is >> in;
  return is;
}

template< typename T1, typename T2 >
inline bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

template< typename T1, typename T2 >
inline bool chmin(T1 &a, T2 b) { return a > b && (a = b, true); }

template< typename T = int64 >
vector< T > make_v(size_t a) {
  return vector< T >(a);
}

template< typename T, typename... Ts >
auto make_v(size_t a, Ts... ts) {
  return vector< decltype(make_v< T >(ts...)) >(a, make_v< T >(ts...));
}

template< typename T, typename V >
typename enable_if< is_class< T >::value == 0 >::type fill_v(T &t, const V &v) {
  t = v;
}

template< typename T, typename V >
typename enable_if< is_class< T >::value != 0 >::type fill_v(T &t, const V &v) {
  for(auto &e : t) fill_v(e, v);
}

template< typename F >
struct FixPoint : F {
  FixPoint(F &&f) : F(forward< F >(f)) {}

  template< typename... Args >
  decltype(auto) operator()(Args &&... args) const {
    return F::operator()(*this, forward< Args >(args)...);
  }
};

template< typename F >
inline decltype(auto) MFP(F &&f) {
  return FixPoint< F >{forward< F >(f)};
}

template< typename Monoid = int, typename OperatorMonoid = Monoid >
struct LinkCutTree {
  using F = function< Monoid(Monoid, Monoid) >;
  using G = function< Monoid(Monoid, OperatorMonoid) >;
  using H = function< OperatorMonoid(OperatorMonoid, OperatorMonoid) >;
  using S = function< Monoid(Monoid) >;

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

    bool rev;
    int sz;

    bool is_root() {
      return !p || (p->l != this && p->r != this);
    }

    Node(int idx, const Monoid &key, const OperatorMonoid &om) :
        idx(idx), key(key), sum(key), lazy(om), sz(1),
        l(nullptr), r(nullptr), p(nullptr), rev(false) {}
  };

  const Monoid M1;
  const OperatorMonoid OM0;
  const F f;
  const G g;
  const H h;
  const S s;

  LinkCutTree() : LinkCutTree([](Monoid a, Monoid b) { return a + b; }, [](Monoid a) { return a; }, Monoid()) {}

  LinkCutTree(const F &f, const S &s, const Monoid &M1) :
      LinkCutTree(f, G(), H(), s, M1, OperatorMonoid()) {}

  LinkCutTree(const F &f, const G &g, const H &h, const S &s,
              const Monoid &M1, const OperatorMonoid &OM0) :
      f(f), g(g), h(h), s(s), M1(M1), OM0(OM0) {}

  Node *make_node(int idx, const Monoid &v = Monoid()) {
    return new Node(idx, v, OM0);
  }

  void propagate(Node *t, const OperatorMonoid &x) {
    t->lazy = h(t->lazy, x);
    t->key = g(t->key, x);
    t->sum = g(t->sum, x);
  }

  void toggle(Node *t) {
    assert(t);
    swap(t->l, t->r);
    t->sum = s(t->sum);
    t->rev ^= true;
  }

  void push(Node *t) {
    if(t->lazy != OM0) {
      if(t->l) propagate(t->l, t->lazy);
      if(t->r) propagate(t->r, t->lazy);
      t->lazy = OM0;
    }
    if(t->rev) {
      if(t->l) toggle(t->l);
      if(t->r) toggle(t->r);
      t->rev = false;
    }
  }

  void update(Node *t) {
    t->sz = 1;
    t->sum = t->key;
    if(t->l) t->sz += t->l->sz, t->sum = f(t->l->sum, t->sum);
    if(t->r) t->sz += t->r->sz, t->sum = f(t->sum, t->r->sum);
  }

  void rotr(Node *t) {
    auto *x = t->p, *y = x->p;
    if((x->l = t->r)) t->r->p = x;
    t->r = x, x->p = t;
    update(x), update(t);
    if((t->p = y)) {
      if(y->l == x) y->l = t;
      if(y->r == x) y->r = t;
      update(y);
    }
  }

  void rotl(Node *t) {
    auto *x = t->p, *y = x->p;
    if((x->r = t->l)) t->l->p = x;
    t->l = x, x->p = t;
    update(x), update(t);
    if((t->p = y)) {
      if(y->l == x) y->l = t;
      if(y->r == x) y->r = t;
      update(y);
    }
  }

  void splay(Node *t) {
    push(t);
    while(!t->is_root()) {
      auto *q = t->p;
      if(q->is_root()) {
        push(q), push(t);
        if(q->l == t) rotr(t);
        else rotl(t);
      } else {
        auto *r = q->p;
        push(r), push(q), push(t);
        if(r->l == q) {
          if(q->l == t) rotr(q), rotr(t);
          else rotl(t), rotr(t);
        } else {
          if(q->r == t) rotl(q), rotl(t);
          else rotr(t), rotl(t);
        }
      }
    }
  }

  Node *expose(Node *t) {
    Node *rp = nullptr;
    for(Node *cur = t; cur; cur = cur->p) {
      splay(cur);
      cur->r = rp;
      update(cur);
      rp = cur;
    }
    splay(t);
    return rp;
  }

  void link(Node *child, Node *parent) {
    expose(child);
    expose(parent);
    child->p = parent;
    parent->r = child;
    update(parent);
  }

  void cut(Node *child) {
    expose(child);
    auto *parent = child->l;
    child->l = nullptr;
    parent->p = nullptr;
    update(child);
  }

  void evert(Node *t) {
    expose(t);
    toggle(t);
    push(t);
  }

  Node *lca(Node *u, Node *v) {
    if(get_root(u) != get_root(v)) return nullptr;
    expose(u);
    return expose(v);
  }

  vector< int > get_path(Node *x) {
    vector< int > vs;
    function< void(Node *) > dfs = [&](Node *cur) {
      if(!cur) return;
      push(cur);
      dfs(cur->r);
      vs.push_back(cur->idx);
      dfs(cur->l);
    };
    expose(x);
    dfs(x);
    return vs;
  }

  void set_propagate(Node *t, const OperatorMonoid &x) {
    expose(t);
    propagate(t, x);
    push(t);
  }

  Node *get_kth(Node *x, int k) {
    expose(x);
    while(x) {
      push(x);
      if(x->r && x->r->sz > k) {
        x = x->r;
      } else {
        if(x->r) k -= x->r->sz;
        if(k == 0) return x;
        k -= 1;
        x = x->l;
      }
    }
    return nullptr;
  }

  Node *get_root(Node *x) {
    expose(x);
    while(x->l) {
      push(x);
      x = x->l;
    }
    return x;
  }
};

int main() {
  int N, Q, S[200000];
  cin >> N >> Q;


  struct Node {
    int64 ans, all, left, right, length;

    Node() : ans(-infll), all(0), left(-infll), right(-infll), length(0) {}

    Node(int64 val, int64 len) : length(len) {
      all = val * len;
      ans = left = right = (val > 0 ? all : val);
    }

    Node operator+(const Node &s) const {
      Node ret;
      ret.length = length + s.length;
      ret.ans = max({ans, s.ans, right + s.left});
      ret.all = all + s.all;
      ret.left = max(left, all + s.left);
      ret.right = max(s.right, right + s.all);
      return ret;
    }
  };
  auto F = [](const Node &a, const Node &b) { return a + b; };
  auto G = [](const Node &a, int64 x) { return Node(x, a.length); };
  auto H = [](int64, int64 y) { return y; };
  auto T = [](Node a) {
    swap(a.left, a.right);
    return a;
  };


  using LCT = LinkCutTree< Node, int64 >;
  LCT lct(F, G, H, T, Node(), infll);
  vector< LCT::Node * > vs(N);

  for(int i = 0; i < N; i++) {
    cin >> S[i];
    vs[i] = lct.make_node(i, Node(S[i], 1));
  }
  for(int i = 0; i < N - 1; i++) {
    int u, v;
    cin >> u >> v;
    --u, --v;
    lct.evert(vs[v]);
    lct.link(vs[v], vs[u]);
  }
  while(Q--) {
    int X, A, B, C;
    cin >> X >> A >> B >> C;
    --A, --B;
    if(X == 1) {
      lct.evert(vs[A]);
      lct.expose(vs[B]);
      lct.set_propagate(vs[B], C);
    } else {
      lct.evert(vs[A]);
      lct.expose(vs[B]);
      cout << vs[B]->sum.ans << "\n";
    }
  }
}


Measured memory_bytes: 33432