#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
using namespace std;
int n,a[100010],b[100010];
struct trees{
	int l,r,sum,st,en,lz;
}tree[400010];
void perhup(int i){
	tree[i].st=tree[i*2].st;
	tree[i].en=tree[i*2+1].en;
	tree[i].sum=tree[i*2].sum+tree[i*2+1].sum;
	if (tree[i*2].en==tree[i*2+1].st){
		tree[i].sum--;
	}
	return ;
}
void build(int i,int l,int r){
	tree[i].l=l;
	tree[i].r=r;
	tree[i].lz=-1e9-1;
	if (l==r){
		tree[i].st=a[l];
		tree[i].en=a[l];
		tree[i].sum=1;
		return ;
	}
	int mid=(l+r)/2;
	build(i*2,l,mid);
	build(i*2+1,mid+1,r);
	perhup(i);
	return ;
}
void pushdown(int i){
	if (tree[i].lz!=-1e9-1){
		tree[i*2].st=tree[i].lz;
		tree[i*2].en=tree[i].lz;
		tree[i*2].sum=1;
		tree[i*2].lz=tree[i].lz;
		tree[i*2+1].st=tree[i].lz;
		tree[i*2+1].en=tree[i].lz;
		tree[i*2+1].sum=1;
		tree[i*2+1].lz=tree[i].lz;
		tree[i].lz=-1e9-1;
	}
	return ;
}

void change(int i,int l,int r,int x){
	if (tree[i].l>=l&&tree[i].r<=r){
		tree[i].en=x;
		tree[i].st=x;
		tree[i].sum=1;
		tree[i].lz=x;
		return ;
	}
	if (tree[i].l>r||tree[i].r<l){
		return ;
	}
	pushdown(i);
	if (tree[i*2].r>=l) change(i*2,l,r,x);
	if (tree[i*2+1].l<=r) change(i*2+1,l,r,x);
	perhup(i);
	return ;
}
int ens=-1e9-1;
int lc=-1e9-1,rc=-1e9-1;
int query(int i,int l,int r){
	int ans=0;
	if (tree[i].l>=l&&tree[i].r<=r){
		if (tree[i].l==l){
			lc=tree[i].st;
		//	printf("lc=%d\n",lc);
		}
		if (tree[i].r==r){
			rc=tree[i].en;
		//	printf("rc=%d\n",rc);
		}
	//	printf("l=%d r=%d sum=%d\n",tree[i].l,tree[i].r,tree[i].sum);
		ans=tree[i].sum;
		if (tree[i*2].en==tree[i*2+1].st) ans--; 
		return tree[i].sum;
	}
	if (tree[i].l>r||tree[i].r<l) return 0;
	pushdown(i);
	if (tree[i].l<l&&tree[i].r>r&&tree[i*2].r>=l&&tree[i*2].r<r){
		ans+=query(i*2,l,r);
		ans+=query(i*2+1,l,r);
		if (tree[i*2].en==tree[i*2+1].st){
			ans--;
		}
		return ans;
	}
	if (tree[i*2].r>=l) ans+=query(i*2,l,r);
	if (tree[i*2+1].l<=r) ans+=query(i*2+1,l,r);
	perhup(i);
	return ans;
}
int en,fi[100010];
struct rec{
	int e,nex;
}z[200010];
void add(int s,int e){
	en++;
	z[en].e=e;
	z[en].nex=fi[s];
	fi[s]=en;
}
int cnt,fa[100010],son[100010],siz[100010],deep[100010],top[100010],id[100010];
void dfs1(int x,int f,int de){
	fa[x]=f;
	siz[x]=1;
	deep[x]=de;
	int p=-1;
	for (int j=fi[x];j!=0;j=z[j].nex){
		int i=z[j].e;
		if (deep[i]==0){
			dfs1(i,x,de+1);
			siz[x]+=siz[i];
			if (p==-1||siz[p]<siz[i]){
				p=i;
			}
		}
	}
	son[x]=p;
	return ;
}
void dfs2(int x,int topp){
	top[x]=topp;
	cnt++;
	id[x]=cnt;
	a[cnt]=b[x];
	if (son[x]==-1){
		return ;
	}
	dfs2(son[x],topp);
	for (int j=fi[x];j!=0;j=z[j].nex){
		int i=z[j].e;
		if (i!=son[x]&&i!=fa[x]){
			dfs2(i,i);
		}
	}
	return ;
}
void qchange(int x,int y,int k){
	while (top[x]!=top[y]){
		if (deep[top[x]]<deep[top[y]]){
			swap(x,y);
		}
		change(1,id[top[x]],id[x],k);
		x=fa[top[x]];
	}
	change(1,min(id[x],id[y]),max(id[x],id[y]),k);
	return ;
}
void qsum(int x,int y){
	int ans1=-1,ans2=-1;
	int ans=0;
	while (top[x]!=top[y]){
		if (deep[top[x]]<deep[top[y]]){
			swap(x,y);
			swap(ans1,ans2);
		}
		ans+=query(1,id[top[x]],id[x]);
	//	printf("lc=%d rc=%d\n",lc,rc);
		if (rc==ans1){
			ans--;
		}
		ans1=lc;
		x=fa[top[x]];
	//	printf("ans1=%d ans2=%d\n",ans1,ans2);
	}
	if (id[x]>id[y]){
		swap(x,y);
		swap(ans1,ans2);
	}
	ans+=query(1,id[x],id[y]);
//	printf("lc=%d rc=%d\nans1=%d ans2=%d\n",lc,rc,ans1,ans2);
	if (rc==ans1){
		ans--;
	}
	if (lc==ans2){
		ans--;
	}
	printf("%d\n",ans);
	return ;
}
char op;
int x,y;
int main(){
	scanf("%d",&n);
	int m;
	scanf("%d",&m);
	for (int i=1;i<=n;i++){
		scanf("%d",&b[i]);
	}
	for (int i=1;i<n;i++){
		int x,y;
		scanf("%d%d",&x,&y);
		add(x,y);
		add(y,x);
	}
	memset(son,-1,sizeof(son));
	dfs1(1,-1,1);
	dfs2(1,1);
	build(1,1,n);
	for (int i=1;i<=m;i++){
		cin>>op;
		scanf("%d%d",&x,&y);
		if (op=='C'){
			int k;
			scanf("%d",&k);
			qchange(x,y,k);
		}
		else{
			qsum(x,y);
		}
	}
	return 0;
}