#include<stdio.h>
#include<vector>
#include<algorithm>
#define int long long
#define N 100005
using namespace std;
int n,m,Lc,Rc,col[N];
int dep[N],fa[N],siz[N],hson[N];
int top[N],id[N],rev[N];
vector<int>e[N];
struct segment_tree{
	#define mid ((l+r)>>1)
	#define lson (k<<1)
	#define rson (k<<1|1)
	int lc[N<<2],rc[N<<2],sum[N<<2],tag[N<<2];
	void updcol(int k,int cl){
		lc[k]=rc[k]=cl;
		sum[k]=1,tag[k]=cl;
	}
	void pushup(int k){
		sum[k]=sum[lson]+sum[rson];
	    if(rc[lson]==lc[rson])--sum[k];
	    lc[k]=lc[lson],rc[k]=rc[rson];
	}
	void pushdown(int k){
		if(!tag[k])return;
		updcol(lson,tag[k]);
		updcol(rson,tag[k]);
		tag[k]=0;
	}
	void buildseg(int k,int l,int r){
	    if(l==r){
	    	lc[k]=rc[k]=col[rev[l]];
	    	sum[k]=1;
	    	return;
	    }
	    buildseg(lson,l,mid);
	    buildseg(rson,mid+1,r);
	    pushup(k);
	}
	void modify(int k,int l,int r,int ql,int qr,int val){
		if(ql<=l && r<=qr){
			updcol(k,val);
			return;
		}
		pushdown(k);
		if(ql<=mid)modify(lson,l,mid,ql,qr,val);
		if(qr>mid)modify(rson,mid+1,r,ql,qr,val);
		pushup(k);
	}
	int query(int k,int l,int r,int ql,int qr){
		if(ql<=l && r<=qr){
			if(l==ql)Lc=lc[k];
			if(r==qr)Rc=rc[k];
			return sum[k];
		}
		pushdown(k);
		if(qr<=mid)return query(lson,l,mid,ql,qr);
	    if(ql>mid)return query(rson,mid+1,r,ql,qr);
	    int res=query(lson,l,mid,ql,qr)+query(rson,mid+1,r,ql,qr);
		if(rc[lson]==lc[rson])--res;
		return res;
	}
	#undef mid
	#undef lson
	#undef rson
}seg;
void dfs1(int k,int F){
	dep[k]=dep[F]+1,fa[k]=F,siz[k]=1;
	int l=e[k].size();
	for(int i=0;i<l;++i){
		int v=e[k][i];
		if(v==F)continue;
		dfs1(v,k);
		siz[k]+=siz[v];
		if(siz[v]>siz[hson[k]])hson[k]=v;
	}
}
int _tot;
void dfs2(int k,int tp){
	top[k]=tp,id[k]=++_tot,rev[_tot]=k;
	if(!hson[k])return;
	dfs2(hson[k],tp);
	int l=e[k].size();
	for(int i=0;i<l;++i){
		int v=e[k][i];
		if(v==fa[k] || v==hson[k])continue;
		dfs2(v,v);
	}
}
void change(int x,int y,int val){
	while(top[x]!=top[y]){
		if(dep[top[x]]<dep[top[y]])swap(x,y);
		seg.modify(1,1,n,id[top[x]],id[x],val);
		x=fa[top[x]];
	}
	if(id[x]>id[y])swap(x,y);
	seg.modify(1,1,n,id[x],id[y],val);
}
int pos1,pos2;
int go(int x,int y){
	int res=0; pos1=0,pos2=0;
	while(top[x]!=top[y]){
		if(dep[top[x]]<dep[top[y]])swap(x,y),swap(pos1,pos2);
		res+=seg.query(1,1,n,id[top[x]],id[x]);
		if(Rc==pos1)--res;
		pos1=Lc,x=fa[top[x]];
	}
	if(id[x]>id[y])swap(x,y),swap(pos1,pos2);
	res+=seg.query(1,1,n,id[x],id[y]);
	if(Lc==pos1)--res;
	if(Rc==pos2)--res;
	return res;
}
signed main(){
	scanf("%lld %lld",&n,&m);
	for(int i=1;i<=n;++i)scanf("%lld",col+i);
	for(int i=1;i<n;++i){
		int u,v; scanf("%lld %lld",&u,&v);
		e[u].push_back(v);
		e[v].push_back(u);
	}
	dfs1(1,0);
	dfs2(1,1);
	seg.buildseg(1,1,n);
	while(m--){
		char opt; int x,y,c;
		scanf(" %c %lld %lld",&opt,&x,&y);
		if(opt=='C'){
			scanf("%lld",&c);
			change(x,y,c);
		}
		else printf("%lld\n",go(x,y));
	}
	return 0;
}