#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
#include<iostream>
#define ll long long 
#define M 4000010
#define mmp make_pair
using namespace std;
int read()
{
	int nm = 0, f = 1;
	char c = getchar();
	for(; !isdigit(c); c = getchar()) if(c == '-') f = -1;
	for(; isdigit(c); c = getchar()) nm = nm * 10 + c - '0';
	return nm * f;
}
int ch[M][10], len[M], fa[M], cnt = 1, cor[100100], n, c;
vector<int> to[100010];
 
int insert(int lst, int c)
{
	int p = ++cnt, f = lst;
	len[p] = len[f] + 1;
	while(f && !ch[f][c]) ch[f][c] = p, f = fa[f];
	if(f == 0)
		fa[p] = 1;
	else{
		int q = ch[f][c];
		if(len[q] == len[f] + 1)
		{
			fa[p] = q;
		}
		else
		{
			int nq = ++cnt;
			fa[nq] = fa[q];
			memcpy(ch[nq], ch[q], sizeof(ch[q]));
			len[nq] = len[f] + 1;
			fa[q] = fa[p] = nq;
			while(f && ch[f][c] == q) ch[f][c] = nq, f = fa[f];
		}
	}	
 	return p;
}
void dfs(int now, int lst, int pre)
{
	int tmp = insert(pre, cor[now]);
	for(int i = 0; i < to[now].size(); i++)
	{
		int vj = to[now][i];
		if(vj == lst) continue;
		dfs(vj, now, tmp);
	}
}
 
int main()
{
	n = read(), c = read();
	for(int i = 1; i <= n; i++) cor[i] = read();
	for(int i = 1; i < n; i++)
	{
		int vi = read(), vj = read();
		to[vi].push_back(vj);
		to[vj].push_back(vi);
	}
	for(int i = 1; i <= n; i++)
	{
		if(to[i].size() == 1)
		{
			dfs(i, i, 1);
		}
	}
 	ll ans = 0;
 	for(int i = 1; i <= cnt; i++) ans += len[i] - len[fa[i]];
	cout << ans << "\n";
	return 0;
}