#include<cstdio>
#include<iostream>
#include<vector>
#include<cstring>
#include<cmath>
#include<algorithm>
#include<ctime>
#include<cstdlib>
#define ll long long
using namespace std;
const int N=1e5+5; 
int n,Q,sign,lc,rc;
int a[N],w[N];
int prt[N],dep[N],sz[N],son[N];
int top[N],pos[N];
char op; 
vector<int>v[N];
void dfs1(int x){
	sz[x]=1;
	for(auto y:v[x]){
		if(y==prt[x])continue;
		dep[y]=dep[x]+1;
		prt[y]=x;
		dfs1(y);
		sz[x]+=sz[y];
		if(sz[y]>sz[son[x]])son[x]=y;
	}
}
void dfs2(int x,int f){
	top[x]=f;
	pos[x]=++sign;
	w[sign]=a[x];
	if(!son[x])return ;
	dfs2(son[x],f);
	for(auto y:v[x]){
		if(y!=prt[x]&&y!=son[x])
			dfs2(y,y);
	}
}
struct Segment_Tree{
	#define mid (l+r>>1)
	#define Ls x<<1,l,mid
	#define Rs x<<1|1,mid+1,r
	int t[N<<2],add[N<<2],lo[N<<2],ro[N<<2];
	void push_up(int x){
		t[x]=t[x<<1]+t[x<<1|1]-(lo[x<<1|1]==ro[x<<1]);
		lo[x]=lo[x<<1];
		ro[x]=ro[x<<1|1]; 
	}
	void push_down(int x){
		if(add[x]){
			t[x<<1]=t[x<<1|1]=1;
			lo[x<<1]=lo[x<<1|1]=ro[x<<1]=ro[x<<1|1]=add[x];
			add[x<<1]=add[x<<1|1]=add[x];
			add[x]=0;
		}
	}
	void build(int x,int l,int r){
		if(l==r){
			t[x]=1;
			lo[x]=ro[x]=w[l];
			return ;
		}
		build(Ls);
		build(Rs);
		push_up(x);
	}
	void upd(int x,int l,int r,int L,int R,int val){
		if(l>=L&&r<=R){
			t[x]=1;
			add[x]=lo[x]=ro[x]=val;
			return ;
		}
		push_down(x);
		if(L<=mid)upd(Ls,L,R,val);
		if(R>mid)upd(Rs,L,R,val);
		push_up(x);
	}
	int ask(int x,int l,int r,int L,int R){
		if(l>=L&&r<=R){
			if(l==L)lc=lo[x];
			if(r==R)rc=ro[x];
			return t[x];
		}
		push_down(x);
//		int ans=0;
//		if(L<=mid)ans+=ask(Ls,L,R);
//		if(R>mid)ans+=ask(Rs,L,R);
//		push_up(x);
//		return ans;
		if(R<=mid)return ask(Ls,L,R);
		if(L>mid)return ask(Rs,L,R);
		int ans=ask(Ls,L,R)+ask(Rs,L,R);
		if(lo[x<<1|1]==ro[x<<1])ans--;
		return ans;
	}
}seg;
inline void Upd(int x,int y,int val){
	int fx=top[x],fy=top[y];
	while(fx!=fy){
		if(dep[fx]<dep[fy])
			swap(x,y),swap(fx,fy);
		seg.upd(1,1,n,pos[fx],pos[x],val);
		x=prt[fx],fx=top[x];
	}
	if(dep[x]>dep[y])swap(x,y);
	seg.upd(1,1,n,pos[x],pos[y],val);
}
inline int Ask(int x,int y){
	int fx=top[x],fy=top[y],px=0,py=0,ans=0;
	while(fx!=fy){
		if(dep[fx]<dep[fy])
			swap(x,y),swap(fx,fy),swap(px,py);
		ans+=seg.ask(1,1,n,pos[fx],pos[x]);
		ans-=(rc==px);
		x=prt[fx],fx=top[x],px=lc;
	}
	if(dep[x]>dep[y])swap(x,y);
	ans+=seg.ask(1,1,n,pos[x],pos[y]);
	ans-=((rc==px)+(lc==py));
	return ans;
}
int main(){
//	freopen(".in","r",stdin);
//	freopen(".out","w",stdout);
	scanf("%d%d",&n,&Q);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]);
	for(int i=1,x,y;i<=n-1;i++){
		scanf("%d%d",&x,&y);
		v[x].push_back(y);
		v[y].push_back(x);
	}
	dfs1(1);
	dfs2(1,1);
	seg.build(1,1,n);
	for(int x,y,z;Q--;){
		scanf("\n%c %d %d",&op,&x,&y);
		if(op=='Q')printf("%d\n",Ask(x,y));
		else scanf("%d",&z),Upd(x,y,z);
	}
	return 0;
}
/*
lemon龙保佑我
6 3
2 2 1 2 1 1
1 2
1 3
2 4
2 5
2 6
Q 3 5
Q 1 2
Q 4 5
*/