C++ :

#include<iostream>
#include<vector>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<queue>
#include<set>
using namespace std;
typedef long long LL;
const int N=3e6;
int gi() {
	int w=0;bool q=1;char c=getchar();
	while ((c<'0'||c>'9') && c!='-') c=getchar();
	if (c=='-') q=0,c=getchar();
	while (c>='0'&&c <= '9') w=w*10+c-'0',c=getchar();
	return q? w:-w;
}
int son[N][10],fa[N],len[N],tot=1;
int c[N];
int head[N],nnext[N],to[N];
inline int add(int p,int c) {
	if (son[p][c]) {
		int q=son[p][c];
		if (len[q]==len[p]+1) return q;
		int nq=++tot;
		len[nq]=len[p]+1;
		fa[nq]=fa[q],fa[q]=nq;
		for (int i=0;i<10;i++) son[nq][i]=son[q][i];
		for (;son[p][c]==q;p=fa[p])
			son[p][c]=nq;
		return nq;
	} else {
		int np=++tot,nq,q;
		len[np]=len[p]+1;
		for (;p&&!son[p][c];p=fa[p])
			son[p][c]=np;
		if (!p) fa[np]=1;
		else if (len[q=son[p][c]]==len[p]+1) fa[np]=q;
		else {
			len[nq=++tot]=len[p]+1;
			fa[nq]=fa[q],fa[q]=fa[np]=nq;
			for (int i=0;i<10;i++) son[nq][i]=son[q][i];
			for (;son[p][c]==q;p=fa[p])
				son[p][c]=nq;
		}
		return np;
	}
}
inline void dfs(int k,int fa,int p) {
	p=add(p,c[k]);
	for (int i=head[k];i;i=nnext[i])
		if (to[i]!=fa)
			dfs(to[i],k,p);
}
int main()
{
#ifndef ONLINE_JUDGE
	freopen("substring.in","r",stdin);
	freopen("substring.out","w",stdout);
#endif
	int a,b,n=gi(),i,tot=0;gi();
	for (i=1;i<=n;i++) c[i]=gi();
	for (i=1;i<n;i++) {
		a=gi(),b=gi();
		to[++tot]=b,nnext[tot]=head[a],head[a]=tot;
		to[++tot]=a,nnext[tot]=head[b],head[b]=tot;
	}
	for (i=1;i<=n;i++) if (!nnext[head[i]]) dfs(i,0,1);
	LL ans=0;
	for (i=1;i<=::tot;i++) ans+=len[i]-len[fa[i]];
	cout<<ans<<endl;
	return 0;
}