#include <stdio.h>
#include <vector>
#include <algorithm>
#define NMax 100010
using namespace std;

const char IN[]="heavypath.in",OUT[]="heavypath.out";

int N,M,L,Lanturi;
int v[NMax],nv[NMax],lant[NMax],nivel[NMax],primulDinLant[NMax],parinteLant[NMax],pozParc[NMax],parcurgere[NMax],T[NMax];
int arb[4*NMax];
vector<int> ad[NMax];

void dfs(int x,int p=0){
	int i;
	T[x]=1;nivel[x]=nivel[p]+1;
	for (i=0;i<(int)ad[x].size();++i) if (ad[x][i]!=p)
		dfs(ad[x][i],x),
		T[x]+=T[ad[x][i]];
}

void makeHeavy(int x,int p=0){

	int i,m=0,next=0;

	pozParc[x]=++L;
	parcurgere[L]=x;
	lant[x]=Lanturi;

	for (i=0;i<(int)ad[x].size();++i) if (ad[x][i]!=p && T[ad[x][i]]>m)
		m=T[ad[x][i]],next=ad[x][i];

	if (!next) return;

	makeHeavy(next,x);

	for (i=0;i<(int)ad[x].size();++i) if (ad[x][i]!=p && ad[x][i]!=next){
		++Lanturi;
		parinteLant[Lanturi]=x;
		primulDinLant[Lanturi]=L+1;
		makeHeavy(ad[x][i],x);
	}
}

void update(int poz,int st,int dr,int x,int val){

	if (st==dr){
		arb[poz]=val;
		return;
	}
	int m=(st+dr)>>1;
	if (x<=m) update(2*poz,st,m,x,val);
	else      update(2*poz+1,m+1,dr,x,val);
	arb[poz]=max(arb[2*poz],arb[2*poz+1]);
}

int query(int poz,int st,int dr,int x,int y){

	if (x<=st && dr<=y)
		return arb[poz];
	int m=(st+dr)>>1,ret=-1;

	if (x<=m) ret=max(ret,query(2*poz,st,m,x,y));
	if (y >m) ret=max(ret,query(2*poz+1,m+1,dr,x,y));

	return ret;
}

void make(int poz,int st,int dr){

	if (st==dr){
		arb[poz]=nv[st];
		return;
	}
	int m=(st+dr)>>1;
	make(2*poz,st,m);
	make(2*poz+1,m+1,dr);
	arb[poz]=max(arb[2*poz],arb[2*poz+1]);
}

int get(int x,int y){

	int ret=-1;

	while (lant[x]!=lant[y]){

		if (nivel[parinteLant[lant[x]]]>nivel[parinteLant[lant[y]]]){
			ret=max(ret,query(1,1,N,primulDinLant[lant[x]],pozParc[x]));
			x=parinteLant[lant[x]];
		}else{
			ret=max(ret,query(1,1,N,primulDinLant[lant[y]],pozParc[y]));
			y=parinteLant[lant[y]];
		}
	}

	if (pozParc[x]>pozParc[y]) swap(x,y);
	ret=max(ret,query(1,1,N,pozParc[x],pozParc[y]));
	return ret;
}

int main()
{
	int i,t,x,y;
	freopen(IN,"r",stdin);
	scanf("%d%d",&N,&M);
	for (i=1;i<=N;++i) scanf("%d",v+i);
	for (i=1;i<N;++i)
	{
		scanf("%d%d",&x,&y);
		ad[x].push_back(y);
		ad[y].push_back(x);
	}

	dfs(1);
	++Lanturi;
	makeHeavy(1);
	for (i=1;i<=N;++i) nv[pozParc[i]]=v[i];
	make(1,1,N);

	freopen(OUT,"w",stdout);
	while (M--){

		scanf("%d%d%d",&t,&x,&y);
		if (t==0){ //UPDATE
			update(1,1,N,pozParc[x],y);
			nv[pozParc[x]]=y;
		}
		else{ //QUERY
			printf("%d\n",get(x,y));
		}
	}
	fclose(stdout);

	return 0;
}