#include<bits/stdc++.h>
using namespace std;
using Int = long long;



struct HLDecomposition {
  int n,pos;
  vector<vector<int> > G;
  vector<int> vid, head, sub, hvy, par, dep, inv, type, ps, pt;
  
  HLDecomposition(){}
  HLDecomposition(int sz):
    n(sz),pos(0),G(n),
    vid(n,-1),head(n),sub(n,1),hvy(n,-1),
    par(n),dep(n),inv(n),type(n),ps(n),pt(n){}
  
  void add_edge(int u, int v) {
    G[u].push_back(v);
    G[v].push_back(u);
  }

  void build(vector<int> rs={0}) {
    int c=0;
    for(int r:rs){
      dfs(r);
      bfs(r, c++);
    }
  }
  
  void dfs(int rt) {
    using T = pair<int, int>;
    stack<T> st;
    par[rt]=-1;
    dep[rt]=0;
    st.emplace(rt,0);
    while(!st.empty()){
      int v=st.top().first;
      int &i=st.top().second;
      if(i<(int)G[v].size()){
	int u=G[v][i++];
	if(u==par[v]) continue;
	par[u]=v;
	dep[u]=dep[v]+1;
	st.emplace(u,0);
      }else{
	st.pop();
	for(int j=0;j<(int)G[v].size();j++){
	  int &u=G[v][j];
	  if(u==par[v]) swap(u,G[v].back());
	  if(u==par[v]) continue;
	  sub[v]+=sub[u];
	  if(sub[u]>sub[G[v].front()]) swap(u,G[v].front());
	}
      }
    }
  }

  void bfs(int r,int c) {
    using T = tuple<int, int, int>;
    stack<T> st;
    st.emplace(r,r,0);
    while(!st.empty()){
      int v,h;
      tie(v,h,ignore)=st.top();
      int &i=get<2>(st.top());
      if(!i){
	type[v]=c;
	ps[v]=vid[v]=pos++;
	inv[vid[v]]=v;
	head[v]=h;
        hvy[v]=(G[v].empty()?-1:G[v][0]);
	if(hvy[v]==par[v]) hvy[v]=-1;
      }
      if(i<(int)G[v].size()){
	int u=G[v][i++];
	if(u==par[v]) continue;
	st.emplace(u,(hvy[v]==u?h:u),0);
      }else{
	st.pop();
	pt[v]=pos;
      }
    }
  }
  
  // for_each(vertex)
  // [l,r] <- attention!!
  void for_each(int u, int v, const function<void(int, int)>& f) {
    while(1){
      if(vid[u]>vid[v]) swap(u,v);
      f(max(vid[head[v]],vid[u]),vid[v]);
      if(head[u]!=head[v]) v=par[head[v]];
      else break;
    }
  }

  template<typename T,typename Q,typename F>
  T for_each(int u,int v,T ti,const Q &q,const F &f){
    T l=ti,r=ti;
    while(1){
      if(vid[u]>vid[v]){
	swap(u,v);
	swap(l,r);
      }
      l=f(l,q(max(vid[head[v]],vid[u]),vid[v]));
      if(head[u]!=head[v]) v=par[head[v]];
      else break;
    }
    return f(l,r);
  }
  
  // for_each(edge)
  // [l,r] <- attention!!
  void for_each_edge(int u, int v, const function<void(int, int)>& f) {
    while(1){
      if(vid[u]>vid[v]) swap(u,v);
      if(head[u]!=head[v]){
	f(vid[head[v]],vid[v]);
        v=par[head[v]];
      }else{
	if(u!=v) f(vid[u]+1,vid[v]);
	break;
      }
    }
  }

  int lca(int u,int v){
    while(1){
      if(vid[u]>vid[v]) swap(u,v);
      if(head[u]==head[v]) return u;
      v=par[head[v]];
    }
  }

  int distance(int u,int v){
    return dep[u]+dep[v]-2*dep[lca(u,v)];
  }
};

template <typename T,typename E,typename F,typename G,typename H>
struct SegmentTree{
  //using F = function<T(T,T)>;
  //using G = function<T(T,E)>;
  //using H = function<E(E,E)>;
  int n,height;
  F f;
  G g;
  H h;
  T ti;
  E ei;
  vector<T> dat;
  vector<E> laz;
  SegmentTree(int n_,F f,G g,H h,T ti,E ei):
    f(f),g(g),h(h),ti(ti),ei(ei){init(n_);}
  void init(int n_){
    n=1;height=0;
    while(n<n_) n<<=1,height++;
    dat.assign(2*n,ti);
    laz.assign(2*n,ei);
  }
  void build(int n_, vector<T> v){
    for(int i=0;i<n_;i++) dat[n+i]=v[i];
    for(int i=n-1;i;i--)
      dat[i]=f(dat[(i<<1)|0],dat[(i<<1)|1]);
  }
  T reflect(int k){
    return g(dat[k],laz[k]);
  }
  inline void eval(int k){
    if(laz[k]==ei) return;
    laz[(k<<1)|0]=h(laz[(k<<1)|0],laz[k]);
    laz[(k<<1)|1]=h(laz[(k<<1)|1],laz[k]);
    dat[k]=reflect(k);
    laz[k]=ei;
  }
  void update(int a,int b,E x){
    a+=n;b+=n-1;
    for(int i=height;i;i--) eval(a>>i);
    for(int i=height;i;i--) eval(b>>i);
    for(int l=a,r=b+1;l<r;l>>=1,r>>=1){
      if(l&1) laz[l]=h(laz[l],x),l++;
      if(r&1) --r,laz[r]=h(laz[r],x);
    }
    while(a>>=1)
      dat[a]=f(reflect((a<<1)|0),reflect((a<<1)|1));
    while(b>>=1)
      dat[b]=f(reflect((b<<1)|0),reflect((b<<1)|1));
  }
  T query(int a,int b){
    a+=n;b+=n-1;
    for(int i=height;i;i--) eval(a>>i);
    for(int i=height;i;i--) eval(b>>i);
    T vl=ti,vr=ti;
    for(int l=a,r=b+1;l<r;l>>=1,r>>=1) {
      if(l&1) vl=f(vl,reflect(l++));
      if(r&1) vr=f(reflect(--r),vr);
    }
    return f(vl,vr);
  }
};

//INSERT ABOVE HERE
signed main(){
  int n,q;
  scanf("%d %d",&n,&q);
  HLDecomposition hld(n);
  vector<int> w(n);
  for(int i=0;i<n;i++) scanf("%d",&w[i]);
  using P = pair<int,int>;
  for(int i=0;i<n-1;i++){
    int a,b;
    scanf("%d %d",&a,&b);
    a--;b--;
    hld.add_edge(a,b);
  }
  hld.build();
  
  using T = tuple<int,int,int,int,int,int,int>;
  
  T ti(-1,-1,-1,-1,-1,-1,-1);
  P ei(-1,-114514);

  auto &par=hld.par;
  auto &vid=hld.vid;;
  auto con=[&](int a,int b){
    return par[a]==b||par[b]==a;
  };
  
  auto f=[&](T a,T b){
    if(a>b) swap(a,b);
    
    if(get<0>(a)<0) return b;
    if(con(get<0>(a),get<1>(b))) swap(a,b);
   
    int al,ar,as,ava,avi,avl,avr;
    tie(al,ar,as,ava,avi,avl,avr)=a;
    int bl,br,bs,bva,bvi,bvl,bvr;
    tie(bl,br,bs,bva,bvi,bvl,bvr)=b;
    
    if(!con(ar,bl)){
      if(con(ar,br)){
	swap(bl,br);
	swap(bvl,bvr);
      }else if(con(al,bl)){
	swap(al,ar);
	swap(avl,avr);
      }else{
	return ti;
      }
    }
    int cl=al,cr=br,cs=as+bs;
    int cva=ava+bva,cvi=max(avi,bvi),cvl=avl,cvr=bvr;
    cvi=max(cvi,avr+bvl);
    cvl=max(cvl,ava+bvl);
    cvr=max(cvr,avr+bva);
    
    return T(cl,cr,cs,cva,cvi,cvl,cvr);
  };
  
  auto g=[&](T a,P p){
    if(p==ei) return a;
    int al,ar,as,ava,avi,avl,avr;
    tie(al,ar,as,ava,avi,avl,avr)=a;
    int v=p.first,b=p.second;
    if(~v) al=ar=v,as=1;
    if(b>=0) return T(al,ar,as,b*as,b*as,b*as,b*as);
    return T(al,ar,as,b*as,b,b,b);
  };
  auto h=[&](P a,P b){return b;};

  SegmentTree<T,P,decltype(f),decltype(g),decltype(h)> seg(n,f,g,h,ti,ei);
  
  vector<T> vt(n);
  for(int i=0;i<n;i++) vt[vid[i]]=g(ti,P(i,w[i]));
  seg.build(n,vt);
  
  while(q--){
    int t,a,b,c;
    scanf("%d %d %d %d",&t,&a,&b,&c);
    a--;b--;
    if(t==1){
      hld.for_each(a,b,[&](int l,int r){
	  seg.update(l,r+1,P(-1,c));
	});
    }
    if(t==2){
      auto ask=[&](int l,int r){return seg.query(l,r+1);};      
      T v=hld.for_each(a,b,seg.ti,ask,seg.f);
      int vl,vr,vs,vva,vvi,vvl,vvr;
      tie(vl,vr,vs,vva,vvi,vvl,vvr)=v;
      printf("%d\n",max({vva,vvi,vvl,vvr}));
    }
  }
  
  return 0;
}



Measured memory_bytes: 52596