#include<bits/stdc++.h>
using namespace std;
#define maxn 100005
struct Edge{int to,nxt;}edge[maxn<<1];
int c[maxn],head[maxn],tot,n;int f[maxn],son[maxn],d[maxn],size[maxn];
int cnt,id[maxn],rk[maxn],top[maxn];
void dfs1(int x,int pre,int deep){size[x]=1,d[x]=deep;for(int i=head[x];i!=-1;i=edge[i].nxt){int y=edge[i].to;if(y==pre)continue;f[y]=x;dfs1(y,x,deep+1);size[x]+=size[y];if(size[son[x]]<size[y])son[x]=y;}
}
void dfs2(int x,int tp){    top[x]=tp;id[x]=++cnt;rk[cnt]=x;if(son[x])dfs2(son[x],tp);for(int i=head[x];i!=-1;i=edge[i].nxt){int y=edge[i].to;if(y!=son[x] && y!=f[x])dfs2(y,y);}
}#define lson l,m,rt<<1
#define rson m+1,r,rt<<1|1
struct Seg{int lc,rc,tot;Seg(){lc=rc=-1;tot=0;}
};
Seg seg[maxn<<2];int lazy[maxn<<2];
Seg pushup(Seg a,Seg b){if(!a.tot)return b;if(!b.tot)return a;Seg res;res.lc=a.lc,res.rc=b.rc;res.tot=a.tot+b.tot;if(a.rc==b.lc)res.tot--;return res;
}
void pushdown(int rt){if(lazy[rt]<0)return;        lazy[rt<<1]=lazy[rt<<1|1]=lazy[rt];seg[rt<<1].lc=seg[rt<<1].rc=lazy[rt];seg[rt<<1].tot=1;seg[rt<<1|1].lc=seg[rt<<1|1].rc=lazy[rt];seg[rt<<1|1].tot=1;lazy[rt]=-1;
}
void build(int l,int r,int rt){if(l==r){seg[rt].lc=seg[rt].rc=c[rk[l]];seg[rt].tot=1;return;}int m=l+r>>1;build(lson);build(rson);seg[rt]=pushup(seg[rt<<1],seg[rt<<1|1]);
}
void update(int L,int R,int c,int l,int r,int rt){if(L<=l && R>=r){lazy[rt]=c;seg[rt].lc=seg[rt].rc=c;seg[rt].tot=1;return;}pushdown(rt);int m=l+r>>1;if(L<=m)update(L,R,c,lson);if(R>m)update(L,R,c,rson);seg[rt]=pushup(seg[rt<<1],seg[rt<<1|1]);
}
Seg query(int L,int R,int l,int r,int rt){if(L<=l && R>=r)return seg[rt];pushdown(rt);int m=l+r>>1;Seg res;if(L<=m)res=pushup(res,query(L,R,lson));if(R>m)res=pushup(res,query(L,R,rson));return res;
}void Update(int x,int y,int c){while(top[x]!=top[y]){if(d[top[x]]<d[top[y]])swap(x,y);update(id[top[x]],id[x],c,1,n,1);x=f[top[x]];}if(id[x]>id[y])swap(x,y);update(id[x],id[y],c,1,n,1);
}
int Query(int x,int y){Seg A,B;while(top[x]!=top[y]){if(d[top[x]]<d[top[y]]){B=pushup(query(id[top[y]],id[y],1,n,1),B);y=f[top[y]];    }else {A=pushup(query(id[top[x]],id[x],1,n,1),A);x=f[top[x]];}}if(id[x]>id[y])A=pushup(query(id[y],id[x],1,n,1),A);else B=pushup(query(id[x],id[y],1,n,1),B);if(A.lc==B.lc)return A.tot+B.tot-1;else return A.tot+B.tot;
}void init(){memset(head,-1,sizeof head);memset(lazy,-1,sizeof lazy);tot=0;
}
void addedge(int u,int v){edge[tot].to=v;edge[tot].nxt=head[u];head[u]=tot++;
}
int main(){init();int q;cin>>n>>q;for(int i=1;i<=n;i++)cin>>c[i];for(int i=1;i<n;i++){int x,y;cin>>x>>y;addedge(x,y);addedge(y,x);}cnt=0;dfs1(1,0,1),dfs2(1,1);build(1,n,1);char op[2];int x,y,z;while(q--){scanf("%s",op);if(op[0]=='Q'){scanf("%d%d",&x,&y);cout<<Query(x,y)<<'\n';}if(op[0]=='C'){scanf("%d%d%d",&x,&y,&z);Update(x,y,z);}}
}