#include <iostream>

 #include <cstdio>

 #include <cstring>

 #include <cmath>

 #include <algorithm>

 #define maxn 100005

 #define maxl 200005

 #define maxm 4000005

 using namespace std;

 typedef long long ll;

 int n,c,cnt,tot,root,last,fa[maxm],du[maxn],dist[maxm],son[maxl],prep[maxl],now[maxn],v[maxn];

 ll ans;

 void add(int x,int y){

     cnt++,prep[cnt]=now[x],now[x]=cnt,son[cnt]=y;

 }

 struct Tsegment{

     int son[maxm][];

     void prepare(){tot=last=root=;memset(dist,,sizeof(dist));}

     int newnode(int x){dist[++tot]=x; return tot;}

     int add(int x,int p){

         int q=son[p][x];

         if (q==){

             int np=newnode(dist[p]+); last=np;

             for (;p&&!son[p][x];p=fa[p]) son[p][x]=np;

             if (p==) fa[np]=root;

             else{

                 q=son[p][x];

                 if (dist[p]+==dist[q]) fa[np]=q;

                 else{

                     int nq=newnode(dist[p]+);

                     memcpy(son[nq],son[q],sizeof(son[q]));

                     fa[nq]=fa[q],fa[q]=fa[np]=nq;

                     for (;p&&son[p][x]==q;p=fa[p]) son[p][x]=nq;

                 }

             }

         }else{

             if (dist[p]+==dist[q]) last=q;

             else{

                 int nq=newnode(dist[p]+); last=nq;

                 memcpy(son[nq],son[q],sizeof(son[q]));

                 fa[nq]=fa[q],fa[q]=nq;

                 for (;p&&son[p][x]==q;p=fa[p]) son[p][x]=nq;

             }

         }

         return last;

     }

 }SAM;

 void dfs(int x,int pa,int goal){

     int p=SAM.add(v[x],goal);

     for (int i=now[x],so=son[i];i;i=prep[i],so=son[i]){

         if (so==pa) continue;

         dfs(so,x,p);

     }

 }

 int main(){

     scanf("%d%d",&n,&c);

     memset(du,,sizeof(du));

     cnt=tot=ans=,memset(now,,sizeof(now));

     for (int i=;i<=n;i++) scanf("%d",&v[i]);

     for (int u,v,i=;i<n;i++) scanf("%d%d",&u,&v),add(u,v),add(v,u),du[u]++,du[v]++;

     SAM.prepare();

     for (int i=;i<=n;i++){

         if (du[i]>) continue;

         dfs(i,,root);

     }

     ans=;

     dist[root]=;

     for (int i=;i<=tot;i++) ans+=(dist[i]-dist[fa[i]]);

     printf("%lld\n",ans);

     return ;

 }