#include<cstdio>
#include<vector>
using namespace std;
const int M=100001;
int n,m,t,x,y,z,o,i,j,k;
int v[M],h[M],s[M],d[M],p[M],e[M],b[M],a[2*M];
vector<int> l[M],c[M];
void D(int x,int p)
{
	int u=0,i,j;
	h[x]=h[p]+1,s[x]=1;
	for(j=l[x].size(),i=0;i<j;++i)
		if(l[x][i]!=p)
		{
			D(l[x][i],x),s[x]+=s[l[x][i]];
			if(s[u]<s[l[x][i]])
				u=l[x][i];
		}
	for(i=0;i<j;++i)
		if(l[x][i]!=p&&l[x][i]!=u)
			b[d[l[x][i]]]=x;
    d[x]=!u?++o:d[u];
	c[d[x]].push_back(x);
}
void U(int p,int v)
{
	for(p+=n,a[p]=v;p>1;p>>=1)
		a[p>>1]=max(a[p],a[p^1]);
}
int Q(int x,int y)
{
	int r=0;
	for(x+=n,y+=n;x<y;x>>=1,y>>=1)
	{
		if(x&1)
			r=max(r,a[x++]);
		if(y&1)
			r=max(r,a[--y]);
	}
	return r;
}
int H(int x,int y)
{
	int r=0;
	while(d[x]!=d[y])
	{
		if(h[b[d[x]]]<h[b[d[y]]])
			swap(x,y);
		r=max(r,Q(p[x],p[c[d[x]].back()]+1)),x=b[d[x]];
	}
	if(p[x]>p[y])
		swap(x,y);
	return max(r,Q(p[x],p[y]+1));
}
int main()
{
	freopen("heavypath.in","r",stdin),freopen("heavypath.out","w",stdout),scanf("%d%d",&n,&m);
	for(i=1;i<=n;++i)
		scanf("%d",v+i);
	for(i=0;i<n-1;++i)
		scanf("%d%d",&x,&y),l[x].push_back(y),l[y].push_back(x);
	for(D(1,0),i=1;i<=o;++i)
		for(k=c[i].size(),j=0;j<k;++j)
			p[c[i][j]]=++z,e[z]=c[i][j],a[z+n]=v[c[i][j]];
	for(i=n;i;--i)
		a[i]=max(a[2*i],a[2*i+1]);
	for(i=0;i<m;i++)
	{
		scanf("%d%d%d",&t,&x,&y);
		if(!t)
			U(p[x],y);
		else if(t==1)
			printf("%d\n",H(x,y));
	}
}