1 #include<cstdio>
  2 #include<cstring>
  3 #include<algorithm>
  4 using namespace std;
  5 const int N=100005;
  6 struct a
  7 {
  8     int cnt;
  9     int lc,rc;
 10 };
 11 int num[N],nmb[N],val[4*N],lcol[4*N],rcol[4*N],laz[4*N];
 12 int siz[N],dep[N],anc[N],imp[N],top[N],dfn[N];
 13 int p[N],noww[2*N],goal[2*N];
 14 int n,m,t1,t2,t3,cnt,tot;
 15 char rd[2];
 16 void link(int f,int t)
 17 {
 18     noww[++cnt]=p[f];
 19     goal[cnt]=t,p[f]=cnt;
 20 }
 21 void DFS(int nde,int fth,int dth)
 22 {
 23     int tmp=0;
 24     siz[nde]=1,anc[nde]=fth,dep[nde]=dth;
 25     for(int i=p[nde];i;i=noww[i])
 26         if(goal[i]!=fth)
 27         {
 28             DFS(goal[i],nde,dth+1);
 29             siz[nde]+=siz[goal[i]];
 30             if(siz[goal[i]]>tmp)
 31                 tmp=siz[goal[i]],imp[nde]=goal[i];
 32         }
 33 }
 34 void MARK(int nde,int tpp)
 35 {
 36     dfn[nde]=++tot,nmb[tot]=num[nde],top[nde]=tpp;
 37     if(imp[nde])
 38     {
 39         MARK(imp[nde],tpp);
 40         for(int i=p[nde];i;i=noww[i])
 41             if(goal[i]!=anc[nde]&&goal[i]!=imp[nde])
 42                 MARK(goal[i],goal[i]);
 43     }
 44 }
 45 void pushup(int nde)
 46 {
 47     int ls=2*nde,rs=2*nde+1;
 48     lcol[nde]=lcol[ls],rcol[nde]=rcol[rs];
 49     val[nde]=val[ls]+val[rs]-(rcol[ls]==lcol[rs]);
 50 }
 51 void create(int nde,int l,int r)
 52 {
 53     if(l==r)
 54         val[nde]=1,lcol[nde]=rcol[nde]=nmb[l];
 55     else
 56     {
 57         int mid=(l+r)/2,ls=2*nde,rs=2*nde+1;
 58         create(ls,l,mid),create(rs,mid+1,r);
 59         pushup(nde);
 60     }
 61 }
 62 void release(int nde,int l,int r)
 63 {
 64     if(laz[nde])
 65     {
 66         int ls=2*nde,rs=2*nde+1;
 67         laz[ls]=lcol[ls]=rcol[ls]=laz[nde];
 68         laz[rs]=lcol[rs]=rcol[rs]=laz[nde];
 69         val[ls]=val[rs]=1; laz[nde]=0;
 70     }
 71 }
 72 void change(int nde,int l,int r,int nl,int nr,int task)
 73 {
 74     if(l>nr||r<nl)
 75         return ;
 76     else if(l>=nl&&r<=nr)
 77         val[nde]=1,lcol[nde]=rcol[nde]=laz[nde]=task;
 78     else
 79     {
 80         int mid=(l+r)/2,ls=2*nde,rs=2*nde+1; release(nde,l,r);
 81         change(ls,l,mid,nl,nr,task),change(rs,mid+1,r,nl,nr,task);
 82         pushup(nde);
 83     }
 84 }
 85 a query(int nde,int l,int r,int nl,int nr)
 86 {
 87     if(l>=nl&&r<=nr)
 88         return (a){val[nde],lcol[nde],rcol[nde]};
 89     else
 90     {
 91         int mid=(l+r)/2,ls=2*nde,rs=2*nde+1; release(nde,l,r);
 92         if(nr<=mid) return query(ls,l,mid,nl,nr);
 93         if(nl>mid) return query(rs,mid+1,r,nl,nr);
 94         a r1=query(ls,l,mid,nl,nr),r2=query(rs,mid+1,r,nl,nr),ret;
 95         ret.lc=r1.lc,ret.rc=r2.rc,ret.cnt=r1.cnt+r2.cnt-(r1.rc==r2.lc);
 96         return ret;
 97     }
 98 }
 99 void path_change(int x,int y,int v)
100 {
101     while(top[x]!=top[y])
102     {
103         if(dep[top[x]]<dep[top[y]]) swap(x,y);
104         change(1,1,n,dfn[top[x]],dfn[x],v); x=anc[top[x]];
105     }
106     if(dep[x]>dep[y]) swap(x,y);
107     change(1,1,n,dfn[x],dfn[y],v); return ;
108 }
109 int path_query(int x,int y)
110 {
111     int rt=0,ll=-1,rr=-1;
112     while(top[x]!=top[y])
113     {
114         if(dep[top[x]]<dep[top[y]]) swap(x,y),swap(ll,rr);
115         a ret=query(1,1,n,dfn[top[x]],dfn[x]); x=anc[top[x]];
116         rt+=ret.cnt-(ll==ret.rc); ll=ret.lc;
117     }
118     if(dep[x]>dep[y]) swap(x,y),swap(ll,rr);
119     a ret=query(1,1,n,dfn[x],dfn[y]); rt+=ret.cnt-(ll==ret.lc)-(rr==ret.rc);
120     return rt;
121 }
122 int main ()
123 {
124     scanf("%d%d",&n,&m);
125     for(int i=1;i<=n;i++)
126         scanf("%d",&num[i]);
127     for(int i=1;i<n;i++)
128         scanf("%d%d",&t1,&t2),link(t1,t2),link(t2,t1);
129     DFS(1,0,1); MARK(1,1); create(1,1,n);
130     while(m--)
131     {
132         scanf("%s",rd);
133         if(rd[0]=='C')
134             scanf("%d%d%d",&t1,&t2,&t3),path_change(t1,t2,t3);
135         else
136             scanf("%d%d",&t1,&t2),printf("%d\n",path_query(t1,t2));
137     }
138     return 0;
139 }