#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#define popcount __builtin_popcount
using namespace std;
typedef long long int ll;
typedef pair<int, int> P;

template<typename Monoid, typename OperatorMonoid=Monoid>
struct LazySegmentTree{
	using F=function<Monoid(Monoid, Monoid)>;
	using G=function<Monoid(Monoid, OperatorMonoid, int)>;
	using H=function<OperatorMonoid(OperatorMonoid, OperatorMonoid)>;
	int sz;
	vector<Monoid> data;
	vector<OperatorMonoid> lazy;
	const F f;
	const G g;
	const H h;
	const Monoid e1;
	const OperatorMonoid e0;

	LazySegmentTree(int n, const F f, const G g, const H h, const Monoid &e1, const OperatorMonoid &e0): f(f), g(g), h(h), e1(e1), e0(e0){
		sz=1;
		while(sz<n) sz<<=1;
		data.resize(2*sz-1, e1);
		lazy.resize(2*sz-1, e0);
	}

	void build(vector<Monoid> v){
		for(int i=0; i<v.size(); i++) data[i+sz-1]=v[i];
		for(int i=sz-2; i>=0; i--) data[i]=f(data[2*i+1], data[2*i+2]);
	}

	void eval(int k, int l, int r){
		if(lazy[k]!=e0){
			data[k]=g(data[k], lazy[k], r-l);
			if(k<sz-1){
				lazy[2*k+1]=h(lazy[2*k+1], lazy[k]);
				lazy[2*k+2]=h(lazy[2*k+2], lazy[k]);
			}
		}
		lazy[k]=e0;
	}

	void update(int a, int b, const OperatorMonoid &x, int k, int l, int r){
		eval(k, l, r);
		if(r<=a || b<=l) return;
		if(a<=l && r<=b){
			lazy[k]=h(lazy[k], x);
			eval(k, l, r);
		}else{
			update(a, b, x, 2*k+1, l, (l+r)/2);
			update(a, b, x, 2*k+2, (l+r)/2, r);
			data[k]=f(data[2*k+1], data[2*k+2]);
		}
	}
	void update(int a, int b, const OperatorMonoid &x){
		return update(a, b, x, 0, 0, sz);
	}

	Monoid find(int a, int b, int k, int l, int r){
		eval(k, l, r);
		if(b<=l || r<=a) return e1;
		if(a<=l && r<=b) return data[k];
		else return f(find(a, b, 2*k+1, l, (l+r)/2), find(a, b, 2*k+2, (l+r)/2, r));
	}
	Monoid find(int a, int b){
		return find(a, b, 0, 0, sz);
	}
	Monoid operator[](const int &k){
		return find(k, k+1);
	}
};

template< typename G=vector<vector<int>> >
struct HeavyLightDecomposition {
  G &g;
  vector< int > sz, in, out, head, rev, par;

  HeavyLightDecomposition(G &g) :
      g(g), sz(g.size()), in(g.size()), out(g.size()), head(g.size()), rev(g.size()), par(g.size()) {}

  void dfs_sz(int idx, int p) {
    par[idx] = p;
    sz[idx] = 1;
    if(g[idx].size() && g[idx][0] == p) swap(g[idx][0], g[idx].back());
    for(auto &to : g[idx]) {
      if(to == p) continue;
      dfs_sz(to, idx);
      sz[idx] += sz[to];
      if(sz[g[idx][0]] < sz[to]) swap(g[idx][0], to);
    }
  }

  void dfs_hld(int idx, int par, int &times) {
    in[idx] = times++;
    rev[in[idx]] = idx;
    for(auto &to : g[idx]) {
      if(to == par) continue;
      head[to] = (g[idx][0] == to ? head[idx] : to);
      dfs_hld(to, idx, times);
    }
    out[idx] = times;
  }

  void build() {
    dfs_sz(0, -1);
    int t = 0;
    dfs_hld(0, -1, t);
  }

  int la(int v, int k) {
    while(1) {
      int u = head[v];
      if(in[v] - k >= in[u]) return rev[in[v] - k];
      k -= in[v] - in[u] + 1;
      v = par[u];
    }
  }

  int lca(int u, int v) {
    for(;; v = par[head[v]]) {
      if(in[u] > in[v]) swap(u, v);
      if(head[u] == head[v]) return u;
    }
  }

  template< typename T, typename Q, typename F >
  T query(int u, int v, const T &ti, const Q &q, const F &f, bool edge = false) {
    T l = ti, r = ti;
    for(;; v = par[head[v]]) {
      if(in[u] > in[v]) swap(u, v), swap(l, r);
      if(head[u] == head[v]) break;
      l = f(q(in[head[v]], in[v] + 1), l);
    }
	l=f(q(in[u] + edge, in[v] + 1), l);
	swap(l.first.first, l.first.second);
    return f(l, r);
//  return {f(q(in[u] + edge, in[v] + 1), l), r};
  }

  template< typename Q >
  void add(int u, int v, const Q &q, bool edge = false) {
    for(;; v = par[head[v]]) {
      if(in[u] > in[v]) swap(u, v);
      if(head[u] == head[v]) break;
      q(in[head[v]], in[v] + 1);
    }
    q(in[u] + edge, in[v] + 1);
  }
};
typedef pair<P, P> PP;
const int INF=2e9+7;
int main()
{
	int n, Q;
	cin>>n>>Q;
	int w[200020];
	for(int i=0; i<n; i++){
		cin>>w[i];
	}
	vector<vector<int>> G(n);
	for(int i=0; i<n-1; i++){
		int s, e;
		cin>>s>>e;
		s--; e--;
		G[s].push_back(e);
		G[e].push_back(s);
	}
	HeavyLightDecomposition<> hld(G);
	hld.build();
	auto f=[](PP a, PP b){
		ll s1a=a.first.first, s2a=a.first.second, sa=a.second.first, sma=a.second.second;
		ll s1b=b.first.first, s2b=b.first.second, sb=b.second.first, smb=b.second.second;
		return PP(P(max(sa+s1b, s1a), max(sb+s2a, s2b)), P(sa+sb, max({sma, smb, s2a+s1b})));
	};
	auto g=[](PP a, int x, int len){
		if(x>=0) return PP(P(x*len, x*len), P(x*len, x*len));
		else return PP(P(x, x), P(x*len, x));
	};
	auto h=[](int x, int y){ return y;};
	PP e=PP(P(-INF, -INF), P(0, -INF));
	LazySegmentTree<PP, int> seg(n, f, g, h, e, -INF);
	vector<PP> v(n);
	for(int i=0; i<n; i++){
		int k=hld.in[i];
		v[k]=PP(P(w[i], w[i]), P(w[i], w[i]));
	}
	seg.build(v);
	for(int z=0; z<Q; z++){
		int t, a, b, c;
		cin>>t>>a>>b>>c;
		a--; b--;
		if(t==1){
			auto q=[&](int i, int j){ seg.update(i, j, c);};
			hld.add(a, b, q);
		}else{
			auto q=[&](int i, int j){ return seg.find(i, j);};
			cout<<hld.query(a, b, e, q, f).second.second<<endl;
		}
	}
	return 0;
}


Measured memory_bytes: 45556