#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using PII = pair<ll, ll>;
#define FOR(i, a, n) for (ll i = (ll)a; i < (ll)n; ++i)
#define REP(i, n) FOR(i, 0, n)
#define ALL(x) x.begin(), x.end()
template<typename T> void chmin(T &a, const T &b) { a = min(a, b); }
template<typename T> void chmax(T &a, const T &b) { a = max(a, b); }
struct FastIO {FastIO() { cin.tie(0); ios::sync_with_stdio(0); }}fastiofastio;
#ifdef DEBUG_ 
#include "../program_contest_library/memo/dump.hpp"
#else
#define dump(...)
#endif
const ll INF = 1LL<<60;

template<typename M>
class LinkCutTree {
public:
    using T = typename M::T;
    using E = typename M::E;

    struct node {
        int sz;
        T val, sum;
        E lazy;
        node *left, *right, *par;
        bool rev;
        node() : sz(1), val(M::T0()), sum(M::T0()), lazy(M::E0()),
            left(nullptr), right(nullptr), par(nullptr), rev(false) {}
        node(T _val) : sz(1), val(_val), sum(_val), lazy(M::E0()),
            left(nullptr), right(nullptr), par(nullptr), rev(false) {}
        inline bool isRoot() const {
            return (!par) || (par->left != this && par->right != this);
        }
        void push() {
            if(lazy != M::E0()) {
                val = M::g(val, lazy, 1), sum = M::g(sum, lazy, sz);
                if(left) left->lazy = M::h(left->lazy, lazy);
                if(right) right->lazy = M::h(right->lazy, lazy);
                lazy = M::E0();
            }
            if(rev) {
                swap(left, right);
                sum = M::s(sum);
                if(left) left->rev ^= true;
                if(right) right->rev ^= true;
                rev = false;
            }
        }
        void eval() {
            sz = 1, sum = val;
            if(left) left->push(), sz += left->sz, sum = M::f(left->sum, sum);
            if(right) right->push(), sz += right->sz, sum = M::f(sum, right->sum);
        }
    };
 
private:
    void rotate(node* u, bool right) {
        node *p = u->par, *g = p->par;
        if(right) {
            if((p->left = u->right)) u->right->par = p;
            u->right = p, p->par = u;
        } else {
            if((p->right = u->left)) u->left->par = p;
            u->left = p, p->par = u;
        }
        p->eval(), u->eval(), u->par = g;
        if(!g) return;
        if(g->left == p) g->left = u;
        if(g->right == p) g->right = u;
        g->eval();
    }
    // uをsplay木の根にする
    void splay(node* u) {
        while(!u->isRoot()) {
            node *p = u->par, *gp = p->par;
            if(p->isRoot()) { // zig
                p->push(), u->push();
                rotate(u, (u == p->left));
            } else {
                gp->push(), p->push(), u->push();
                bool flag = (u == p->left);
                if((u == p->left) == (p == gp->left)) { // zig-zig
                    rotate(p, flag), rotate(u, flag);
                } else { // zig-zag
                    rotate(u, flag), rotate(u, !flag);
                }
            }
        }
        u->push();
    }
    // 頂点uから根へのパスをつなげる
    node* expose(node* u) {
        node* last = nullptr;
        for(node* v = u; v; v = v->par) {
            splay(v);
            v->right = last;
            v->eval();
            last = v;
        }
        splay(u);
        return last;
    }
    void evert(node* u) {
        expose(u), u->rev = !(u->rev), u->push();
    }
    bool connected(node *u, node *v) {
        expose(u), expose(v);
        return u == v || u->par;
    }
    void link(node *u, node *v) {
        evert(u), u->par = v;
    }
    void cut(node* u) { // uと親の辺を切る
        expose(u), u->left->par = nullptr, u->left = nullptr, u->eval();
    }
    void cut(node* u, node* v) {
        expose(u), expose(v);
        if(u->isRoot()) u->par = nullptr;
        else v->left->par = nullptr, v->left = nullptr, v->eval();
    }
    node* lca(node* u, node* v) {
        expose(u);
        return expose(v);
    }
    int depth(node* u) {
        expose(u);
        return u->sz - 1;
    }
    void toRoot_range(node* u, const E x) {
        expose(u);
        u->lazy = M::h(u->lazy, x), u->push();
    }
    void range(node* u, node* v, const E x) {
        evert(u), expose(v);
        v->lazy = M::h(v->lazy, x), v->push();
    }
    void toRoot_query(node* u) {
        expose(u);
        return u->sum;
    }
    T query(node* u, node* v) {
        evert(u), expose(v);
        return v->sum;
    }
 
public:
    const int n;
    node** arr;
    LinkCutTree(const vector<T> &v) : n(v.size()) { 
        arr = new node*[n];
        REP(i, n) arr[i] = new node(v[i]);
    }
    // ~LinkCutTree(){
    //     REP(i, n) delete arr[i];
    //     delete[] arr;
    // }
    bool connected(int id1, int id2){ return connected(arr[id1], arr[id2]); }
    void link(int id1, int id2){ return link(arr[id1], arr[id2]); }
    void cut(int id){ return cut(arr[id]); } // uと親の辺を切る
    void cut(int id1, int id2){ return cut(arr[id1], arr[id2]); }
    int lca(int id1, int id2){ return static_cast<size_t>(lca(arr[id1], arr[id2]) - arr[0]); }
    void evert(int id){ return evert(arr[id]); }
    int depth(int id){ return depth(arr[id]); }
    void toRoot_range(int id, const E x){ return toRoot_range(arr[id], x); }
    void range(int id1, int id2, const E x){ return range(arr[id1], arr[id2], x); }
    T toRoot_query(int id){ return toRoot_query(arr[id]); }
    T query(int id1, int id2){ return query(arr[id1], arr[id2]); }
};

struct submax { 
    ll lsum, rsum, max, sum;
    submax() {}
    submax(ll a, ll b, ll c, ll d) : lsum(a), rsum(b), max(c), sum(d) {}
};
struct monoid {
    using T = submax;
    using E = ll;
    static T T0() { return submax(-INF, -INF, -INF, 0); }
    static constexpr E E0() { return INF; }
    static T f(const T &x, const T &y) { 
        T ret;
        ret.lsum = max(x.lsum, x.sum+y.lsum);
        ret.rsum = max(y.rsum, x.rsum+y.sum);
        ret.max = max({x.max, y.max, x.rsum+y.lsum});
        ret.sum = x.sum + y.sum;
        return ret; 
    }
    static T g(const T &x, const E &y, int sz) { 
        T ret;
        ret.max = max(y, y*sz);
        ret.sum = y * sz;
        ret.lsum = ret.max;
        ret.rsum = ret.max;
        return ret;
    }
    static E h(const E &x, const E &y) { 
        return y;
    }
    static T s(const T &x) { 
        T ret(x);
        swap(ret.lsum, ret.rsum);
        return ret;
    }
};

int main(void) {
    ll n, q;
    cin >> n >> q;
    vector<ll> w(n);
    REP(i, n) cin >> w[i];
    vector<submax> init(n);
    REP(i, n) init[i] = submax(w[i], w[i], w[i], w[i]);
    LinkCutTree<monoid> lct(init);
    REP(i, n-1) {
        ll u, v;
        cin >> u >> v;
        u--, v--;
        lct.link(u, v);
    }
    REP(i, q) {
        ll t, a, b, c;
        cin >> t >> a >> b >> c;
        a--, b--;
        if(t == 1) {
            lct.range(a, b, c);
        } else {
            cout << lct.query(a, b).max << "\n";
        }
    }

    return 0;
}


Measured memory_bytes: 37172