#include <cstdio>
#include <algorithm>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <queue>
#include <iostream>
using namespace std;
#define N 100005
#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
int sum[N<<2],lcol[N<<2],rcol[N<<2],cov[N<<2];
int head[N],cnt,dep[N],anc[N],fa[N],siz[N],son[N];
int idx[N],a[N],p[N],tims,n,Q;
struct node
{int to,next;
}e[N<<1];
void add(int x,int y)
{e[cnt].to=y;e[cnt].next=head[x];head[x]=cnt++;return ;
}
void dfs1(int x,int from)
{fa[x]=from,siz[x]=1,dep[x]=dep[from]+1;for(int i=head[x];i!=-1;i=e[i].next){int to1=e[i].to;if(to1!=from){dfs1(to1,x);siz[x]+=siz[to1];if(siz[son[x]]<siz[to1])son[x]=to1;}}
}
void dfs2(int x,int top)
{idx[x]=++tims;p[tims]=x;anc[x]=top;if(son[x])dfs2(son[x],top);for(int i=head[x];i!=-1;i=e[i].next){int to1=e[i].to;if(to1!=fa[x]&&to1!=son[x]){dfs2(to1,to1);}}
}
void PushUp(int rt)
{lcol[rt]=lcol[rt<<1];rcol[rt]=rcol[rt<<1|1];sum[rt]=sum[rt<<1|1]+sum[rt<<1];if(lcol[rt<<1|1]==rcol[rt<<1])sum[rt]--;return ;
}
void PushDown(int rt)
{if(cov[rt]){cov[rt<<1]=cov[rt<<1|1]=lcol[rt<<1]=rcol[rt<<1]=lcol[rt<<1|1]=rcol[rt<<1|1]=cov[rt];sum[rt<<1]=sum[rt<<1|1]=1;cov[rt]=0;}
}
void build(int l,int r,int rt)
{if(l==r){sum[rt]=1;lcol[rt]=rcol[rt]=a[p[l]];return ;}int m=(l+r)>>1;build(lson);build(rson);PushUp(rt);
}
void Update(int L,int R,int c,int l,int r,int rt)
{if(L<=l&&r<=R){lcol[rt]=rcol[rt]=cov[rt]=c;sum[rt]=1;return ;}PushDown(rt);int m=(l+r)>>1;if(m>=L)Update(L,R,c,lson);if(m<R)Update(L,R,c,rson);PushUp(rt);
}
int query(int L,int R,int l,int r,int rt)
{if(L<=l&&r<=R)return sum[rt];PushDown(rt);int m=(l+r)>>1;int ret=0,vis=0;if(m>=L){vis++;ret+=query(L,R,lson);}if(m<R){vis++;ret+=query(L,R,rson);}if(rcol[rt<<1]==lcol[rt<<1|1]&&vis==2)ret--;return ret;
}
int query_col(int x,int l,int r,int rt)
{if(l==r){return lcol[rt];}PushDown(rt);int m=(l+r)>>1;if(m>=x)return query_col(x,lson);else return query_col(x,rson);
}
int get_lca_query(int x,int y)
{int ret=0;while(anc[x]!=anc[y]){if(dep[anc[x]]<dep[anc[y]])swap(x,y);ret+=query(idx[anc[x]],idx[x],1,n,1);int l=query_col(idx[anc[x]],1,n,1);int r=query_col(idx[fa[anc[x]]],1,n,1);if(l==r)ret--;x=fa[anc[x]];}if(dep[x]>dep[y])swap(x,y);ret+=query(idx[x],idx[y],1,n,1);return ret;
}
void get_lca_Update(int x,int y,int c)
{while(anc[x]!=anc[y]){if(dep[anc[x]]<dep[anc[y]])swap(x,y);Update(idx[anc[x]],idx[x],c,1,n,1);x=fa[anc[x]];}if(dep[x]>dep[y])swap(x,y);Update(idx[x],idx[y],c,1,n,1);return ;
}
char s[20];
int main()
{memset(head,-1,sizeof(head));scanf("%d%d",&n,&Q);for(int i=1;i<=n;i++){scanf("%d",&a[i]);}for(int i=1;i<n;i++){int x,y;scanf("%d%d",&x,&y);add(x,y);add(y,x);}dfs1(1,0);dfs2(1,1);build(1,n,1);while(Q--){int x,y,z;scanf("%s%d%d",s,&x,&y);if(s[0]=='Q'){printf("%d\n",get_lca_query(x,y));}else{scanf("%d",&z);get_lca_Update(x,y,z);}}return 0;
}