#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_DEPRECATE

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <limits>
#include <cfloat>
#include <ctime>
#include <cassert>
#include <map>
#include <utility>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <complex>
#include <stack>
#include <queue>
#include <numeric>
#include <list>
#include <iomanip>
#include <fstream>
#include <iterator>
#include <bitset>

using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> Pii;
typedef pair<ll, ll> Pll;

#define FOR(i,n) for(int i = 0; i < (n); i++)
#define sz(c) ((int)(c).size())
#define ten(x) ((int)1e##x)
#define tenll(x) ((ll)1e##x)

#pragma comment(linker,"/STACK:36777216")

//heavy-light decomposition
class HL_decomposition {
public:
	const vector<vector<int>>& e;
	const int n;
	vector<int> par, depth, ord; //???,???±?????????????????????????????????
	vector<int> cluster; //decomposition???????????????????????????????????±??????????
	vector<vector<int> > pathes; //?????????????????????????????????????????????
	vector<int> path_idx; // path_idx[v] = ?????¨??????????§???index

	void init(int v) {
		depth.resize(n, 0);
		par.resize(n, 0);
		ord.resize(n, 0);

		depth[v] = 0;
		par[v] = -1;
		ord[0] = v; //ord????????\??????¨???????????????bfs??????
		for (int p = 0, r = 1; p < r; p++) {
			int cur = ord[p];
			for (int nv : e[cur]) {
				if (nv == par[cur]) continue;
				ord[r++] = nv;
				par[nv] = cur;
				depth[nv] = depth[cur] + 1;
			}
		}
	}

	void decomposition() {
		vector<int> subtree_size(n, 1);
		for (int i = n - 1; i > 0; i--) subtree_size[par[ord[i]]] += subtree_size[ord[i]];
		cluster.resize(n, -1);
		int cluster_type = 0;
		FOR(i, n) {
			int u = ord[i];
			if (cluster[u] == -1) cluster[u] = cluster_type++;
			int max_subsize = -1, selected = -1;
			for (int v : e[u]) {
				if (par[u] != v && max_subsize < subtree_size[v]) {
					max_subsize = subtree_size[v];
					selected = v;
				}
			}
			if (selected != -1) cluster[selected] = cluster[u];
		}
	}

	void enum_pathes() {
		int cluster_num = 0;
		vector<int> rp(n);
		FOR(i, n) {
			rp[cluster[i]]++;
			cluster_num = max(cluster_num, cluster[i]);
		}
		cluster_num++;
		pathes.resize(cluster_num);
		FOR(i, cluster_num) pathes[i].resize(rp[i]);
		for (int i = n - 1; i >= 0; i--) {
			int u = ord[i];
			pathes[cluster[u]][--rp[cluster[u]]] = u;
		}
	}

	void set_path_idx() {
		path_idx.resize(n);
		for (const vector<int>& path : pathes) {
			FOR(i, sz(path)) path_idx[path[i]] = i;
		}
	}

public:
	HL_decomposition(const vector<vector<int>>& e) : e(e), n(sz(e)) {
		init(0);
		decomposition();
		enum_pathes();
		set_path_idx();
	}
};

const int INF = ten(9);

struct A {
	int left, right, ans, all;
	bool lazyflag;
	short lazyval;
	A& reverse() {
		std::swap(left, right);
		return *this;
	}
};

class DouseTree {
	int n;
	mutable std::vector<A> node;
	void update(int a, int b, short x, int k, int l, int r) {
		if (r <= a || b <= l)return;
		if (a <= l && r <= b) {
			A &v = node[k];
			v.left = v.right = v.ans = x <= 0 ? x : x*(r - l);
			v.all = x*(r - l);
			v.lazyflag = true;
			v.lazyval = x;
			return;
		}
		int m = (l + r) / 2;
		if (node[k].lazyflag) {
			update(l, r, node[k].lazyval, 2 * k + 1, l, m);
			update(l, r, node[k].lazyval, 2 * k + 2, m, r);
			node[k].lazyflag = false;
		}
		update(a, b, x, 2 * k + 1, l, m);
		update(a, b, x, 2 * k + 2, m, r);
		node[k] = func(node[2 * k + 1], node[2 * k + 2]);
	}
	A query(int a, int b, int k, int l, int r) {
		if (r <= a || b <= l)return identity();
		if (a <= l && r <= b) {
			return node[k];
		}
		int m = (l + r) / 2;
		if (node[k].lazyflag) {
			update(l, r, node[k].lazyval, 2 * k + 1, l, m);
			update(l, r, node[k].lazyval, 2 * k + 2, m, r);
			node[k].lazyflag = false;
		}
		return func(query(a, b, 2 * k + 1, l, m), query(a, b, 2 * k + 2, m, r));
	}
public:
	static A identity() {
		A res = { -INF, -INF, -INF, 0, false };
		return res;
	}
	static A func(const A &a, const A &b) {
		if (a.left == -INF)return b;
		if (b.left == -INF)return a;
		A res;
		res.left = max(a.left, a.all + b.left);
		res.right = max(b.right, a.right + b.all);
		res.ans = max(max(a.ans, b.ans), a.right + b.left);
		res.all = a.all + b.all;
		res.lazyflag = false;
		return res;
	}
	DouseTree(vector<short>& vals) {
		init(sz(vals));
		FOR(i, sz(vals)) {
			auto &nd = node[i + n - 1];
			nd.all = nd.ans = nd.left = nd.right = vals[i];
		}
		for (int i = n - 2; i >= 0; i--) {
			node[i] = func(node[i * 2 + 1], node[i * 2 + 2]);
		}
	}
	void init(int n) {
		while (n&(n - 1))n += n&-n;
		this->n = n;
		node.assign(2 * n - 1, identity());
	}
	void update(int a, int b, int x) {
		update(a, b, x, 0, 0, n);
	}
	A query(int a, int b) {
		return query(a, b, 0, 0, n);
	}
};


class LCA {
public:
	vector<vector<int>>& e;
	int V, logV;
	vector<int> depth;
	vector<vector<int> > parent;

	LCA(vector<vector<int>>& e) : e(e) {
		this->V = sz(e);
		logV = 0;
		while (V >= (1 << logV)) logV++;
		this->depth = vector<int>(V);
		this->parent = vector<vector<int> >(logV, vector<int>(V));

		dfs(0, -1, 0);
		build();
	}

	void dfs(int v, int par, int d) {
		depth[v] = d;
		parent[0][v] = par;
		for (auto to : e[v]) {
			if (par == to) continue;
			dfs(to, v, d + 1);
		}
	}

	void build() {
		for (int k = 0; k + 1 < logV; k++) {
			for (int v = 0; v < V; v++) {
				if (parent[k][v] < 0) parent[k + 1][v] = -1;
				else parent[k + 1][v] = parent[k][parent[k][v]];
			}
		}
	}

	int prev_parent(int u, int par) {
		for (int k = logV - 1; k >= 0; k--) {
			int diff = depth[u] - depth[par];
			if ((diff - (1 << k)) > 0) {
				u = parent[k][u];
			}
		}
		return u;
	}

	int query(int u, int v) {
		if (depth[u] > depth[v]) swap(u, v);
		for (int k = 0; k < logV; k++) {
			if ((depth[v] - depth[u]) >> k & 1)
				v = parent[k][v];
		}
		if (u == v) return u;

		for (int k = logV - 1; k >= 0; k--) {
			if (parent[k][u] != parent[k][v]) {
				u = parent[k][u];
				v = parent[k][v];
			}
		}
		return parent[0][u];
	}
};

class tree_query {
	LCA* lca;
	HL_decomposition *hl;
	vector<DouseTree*> rmqs;
public:
	tree_query(vector<vector<int>>& e, vector<short>& a) {
		lca = new LCA(e);
		hl = new HL_decomposition(e);
		rmqs.resize(sz(hl->pathes));
		FOR(i, sz(rmqs)) {
			vector<short> vals;
			for (auto x : hl->pathes[i]) vals.push_back(a[x]);
			rmqs[i] = new DouseTree(vals);
		}
	}

	// u -- v ??? u -- lca(u,v) , v - lca(u,v)?????? ????????????
	pair<Pii, Pii> expose(int u, int v) {
		auto l = lca->query(u, v);
		int l2 = -1;
		if (l != v) l2 = lca->prev_parent(v, l);
		return make_pair(Pii(u, l), Pii(v, l2));
	}

	void update_core(int u, int par, int val) {
		if (par == -1) return;
		while (true) {
			int l_index = 0;
			const int my_cluster = hl->cluster[u];
			if (my_cluster == hl->cluster[par]) l_index = hl->path_idx[par];
			rmqs[my_cluster]->update(l_index, hl->path_idx[u] + 1, val);
			if (my_cluster == hl->cluster[par]) break;
			u = hl->par[hl->pathes[my_cluster][0]];
		}
	}

	void update(int u, int v, int val) {
		auto ep = expose(u, v);
		update_core(ep.first.first, ep.first.second, val);
		update_core(ep.second.first, ep.second.second, val);
	}

	A query_core(int u, int par) {
		A ret = DouseTree::identity();
		if (par == -1) return ret;
		while (true) {
			int l_index = 0;
			const int my_cluster = hl->cluster[u];
			if (my_cluster == hl->cluster[par]) l_index = hl->path_idx[par];
			auto cur = rmqs[hl->cluster[u]]->query(l_index, hl->path_idx[u] + 1);
			ret = DouseTree::func(cur, ret);
			if (my_cluster == hl->cluster[par]) break;
			u = hl->par[hl->pathes[my_cluster][0]];
		}
		return ret;
	}

	ll query(int u, int v) {
		auto ep = expose(u, v);
		auto ans1 = query_core(ep.first.first, ep.first.second);
		auto ans2 = query_core(ep.second.first, ep.second.second);

		auto ans = DouseTree::func(ans1.reverse(), ans2);
		return ans.ans;
	}

	~tree_query() {
		delete lca;
		delete hl;
		FOR(i, sz(rmqs)) delete rmqs[i];
	}
};

#ifdef _WIN32
#   define mygc(c) (c)=getchar()
#   define mypc(c) putchar(c)
#else
#   define mygc(c) (c)=getchar_unlocked()
#   define mypc(c) putchar_unlocked(c)
#endif

void reader(short &x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = (x)* 10 + k - '0'; }if (m)(x) = -(x); }
void reader(int &x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = (x)* 10 + k - '0'; }if (m)(x) = -(x); }
void reader(ll &x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = (x) * 10 + k - '0'; }if (m)(x) = -(x); }
int reader(char c[]) { int i, s = 0; for (;;) { mygc(i); if (i != ' '&&i != '\n'&&i != '\r'&&i != '\t'&&i != EOF) break; }c[s++] = i; for (;;) { mygc(i); if (i == ' ' || i == '\n' || i == '\r' || i == '\t' || i == EOF) break; c[s++] = i; }c[s] = '\0'; return s; }
template <class T, class S> void reader(T& x, S& y) { reader(x); reader(y); }
template <class T, class S, class U> void reader(T& x, S& y, U& z) { reader(x); reader(y); reader(z); }
template <class T, class S, class U, class V> void reader(T& x, S& y, U& z, V& w) { reader(x); reader(y); reader(z); reader(w); }

void writer(int x, char c) { int s = 0, m = 0; char f[10]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(ll x, char c) { int s = 0, m = 0; char f[20]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(const char c[]) { int i; for (i = 0; c[i] != '\0'; i++)mypc(c[i]); }
void writer(const char x[], char c) { int i; for (i = 0; x[i] != '\0'; i++)mypc(x[i]); mypc(c); }
template<class T> void writerLn(T x) { writer(x, '\n'); }
template<class T, class S> void writerLn(T x, S y) { writer(x, ' '); writer(y, '\n'); }
template<class T, class S, class U> void writerLn(T x, S y, U z) { writer(x, ' '); writer(y, ' '); writer(z, '\n'); }
template<class T> void writerArr(T x[], int n) { if (!n) { mypc('\n'); return; }FOR(i, n - 1)writer(x[i], ' '); writer(x[n - 1], '\n'); }

int main() {
	int n, m; reader(n, m);
	vector<short> v(n);
	FOR(i, n) reader(v[i]);
	vector<vector<int>> e(n);
	FOR(i, n - 1) {
		int a, b; reader(a, b);
		a--; b--;
		e[a].push_back(b);
		e[b].push_back(a);
	}

	tree_query tq(e, v);

	FOR(i, m) {
		int t, a, b, c; reader(t, a, b, c);
		a--; b--;
		if (t == 1) {
			tq.update(a, b, c);
		} else {
			ll ans = tq.query(a, b);
			writerLn(ans);
		}
	}
}

Measured memory_bytes: 59988