#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cstring>
#define lson rt<<1
#define rson rt<<1|1
#define Lson l,m,lson
#define Rson m+1,r,rson
typedef long long LL;
using namespace std;
const int maxn =1e5+5;
struct Edge{int to,next;
}E[2*maxn];
int n,head[maxn],tot;
int cnt,idx,size[maxn],fa[maxn],son[maxn],dep[maxn],top[maxn],id[maxn],rnk[maxn];
int a[maxn];
void init()
{   cnt=idx=tot=0;memset(head,-1,sizeof(head));dep[1]=0,fa[1]=1,size[0]=0;memset(son,0,sizeof(son));
}void AddEdge(int u,int v)
{E[tot] = (Edge){v,head[u]};head[u]=tot++;
}
void dfs1(int u)
{size[u]=1;for(int i=head[u];~i;i=E[i].next){int v=E[i].to;if(v!=fa[u]){fa[v]=u;dep[v]=dep[u]+1;dfs1(v);size[u]+=size[v];if(size[son[u]]<size[v]) son[u]=v;}}
}void dfs2(int u,int topu)
{top[u]= topu;id[u] = ++idx;rnk[idx] = u;if(!son[u]) return;dfs2(son[u],top[u]);for(int i=head[u];~i;i=E[i].next){int v=E[i].to;if(v!=fa[u]&&v!=son[u]) dfs2(v,v);}
}struct Node{int sum,add,lc,rc;
}tree[maxn<<2];
int Lc,Rc;
void pushup(int rt){                //区间合并tree[rt].sum = tree[lson].sum + tree[rson].sum; tree[rt].lc = tree[lson].lc;tree[rt].rc = tree[rson].rc;if(tree[lson].rc==tree[rson].lc)tree[rt].sum--;
}
void pushdown(int l,int r,int rt){if(tree[rt].add){tree[lson].add = tree[rson].add = 1;tree[lson].sum = tree[rson].sum = 1;tree[lson].lc = tree[lson].rc = tree[rt].lc;tree[rson].lc = tree[rson].rc = tree[rt].lc;tree[rt].add = 0;}
}void build(int l,int r,int rt)
{tree[rt].add = 0;if(l==r){tree[rt].sum = 1;tree[rt].lc = tree[rt].rc = a[rnk[l]];return;}int m = (l+r)>>1;build(Lson);build(Rson);pushup(rt);
}void update(int L,int R,int col,int l=1,int r=n,int rt=1){if(L<=l && R>=r){tree[rt].sum = tree[rt].add =1;tree[rt].lc = tree[rt].rc = col;return ;}pushdown(l,r,rt);int m =(l+r)>>1;if(L<=m) update(L,R,col,Lson);if(R>m) update(L,R,col,Rson);pushup(rt);
}int query(int L,int R,int l=1,int r=n,int rt=1){        //单点if(L==l) Lc = tree[rt].lc;if(R==r) Rc = tree[rt].rc;if(L<=l && R>=r)return tree[rt].sum;pushdown(l,r,rt);int m = (l+r)>>1 , ans=0; bool left = false;if(L<=m) {ans+=query(L,R,Lson);left = true;}if(R>m){ans +=query(L,R,Rson);if(left && tree[lson].rc ==tree[rson].lc) ans--;} pushup(rt);return ans;
}void CHANGE(int u,int v,int col)
{while(top[u]!=top[v]){if(dep[top[u]]<dep[top[v]]) swap(u,v);update(id[top[u]],id[u],col);u = fa[top[u]];    }if(dep[u]>dep[v]) swap(u,v);update(id[u],id[v],col);
}int Qsum(int u,int v)
{int c1=-1,c2=-1, ans=0;     //记录上条链最左侧的颜色while(top[u]!=top[v]){if(dep[top[u]]<dep[top[v]]){swap(u,v);swap(c1,c2);        }ans +=query(id[top[u]],id[u]);if(Rc == c1) ans--;c1 = Lc;u = fa[top[u]];}if(dep[u]>dep[v]){swap(u,v);swap(c1,c2);}ans += query(id[u],id[v]);if(Lc==c1) ans--;if(Rc==c2) ans--;return ans;
}int main()
{#ifndef ONLINE_JUDGEfreopen("in.txt","r",stdin);freopen("out.txt","w",stdout);#endifint m,q,u,v;char op[5];while(scanf("%d%d",&n,&m)==2){init();for(int i=1;i<=n;++i) scanf("%d",&a[i]);for(int i=1;i<n;++i){scanf("%d%d",&u,&v);AddEdge(u,v);AddEdge(v,u);}dfs1(1);dfs2(1,1);build(1,n,1);while(m--){scanf("%s",op);if(op[0]=='Q'){scanf("%d%d",&u,&v);printf("%d\n",Qsum(u,v));}else{int col;scanf("%d%d%d",&u,&v,&col);CHANGE(u,v,col);}}}return 0;
}