#include<cstdio>

#include<iostream>

#include<cstring>

#include<algorithm>

#include<vector>

using namespace std;

struct node{

    node* c[];int id;

    node(){memset(c,,sizeof(c));}

};

#define maxn 101000

vector<int> e[maxn];

#define pb push_back

int a[maxn],pre[maxn];

inline void bfs(int x,node *&y){

    if (!y) y=new node;

    static int q[maxn];

    static node * p[maxn];

    q[]=x;

    p[]=y;

    pre[x]=;

    for (int l=,r=,u=q[];l<=r;u=q[++l]) {

        for (vector<int>::iterator i=e[u].begin();i!=e[u].end();++i) {

            if (*i==pre[u]) continue;

            pre[*i]=u;q[++r]=*i;

            if (!p[l]->c[a[*i]]) p[l]->c[a[*i]]=new node;

            p[r]=p[l]->c[a[*i]];

        }

    }

}

struct snode{int ch[],l,fa;}s[maxn*];

typedef long long ll;

int cnt;ll ans;

inline void add(int x,node* u) {

    int p=++cnt,t=u->id;

    u->c[x]->id=p;

    s[p].l=s[t].l+;

    for (;t!=-&&!s[t].ch[x];t=s[t].fa) s[t].ch[x]=p;

    if (t==-) s[p].fa=;

    else if (s[t].l+==s[s[t].ch[x]].l) s[p].fa=s[t].ch[x];

    else {

        int r=++cnt,q=s[t].ch[x];

        s[r]=s[q];s[r].l=s[t].l+;

        s[p].fa=s[q].fa=r;

        for (;t!=-&&s[t].ch[x]==q;t=s[t].fa) s[t].ch[x]=r;

    }

    ans+=s[p].l-s[s[p].fa].l;

}

int c;

node *root;

inline void build(){

    static node *q[maxn*];

    q[]=root;

    root->id=;

    s[].fa=-;

    for (int l=,r=;l<=r;l++) {

        node *u=q[l];

        for (int i=;i<=c;i++)

            if (u->c[i]) {

                add(i,u);

                q[++r]=u->c[i];

            }

    }

}

int main(){

    int n;

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

    for (int i=;i<=n;i++) scanf("%d",a+i);

    for (int i=;i<=n;i++) a[i]++;

    root=new node;

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

        int x,y;

        scanf("%d%d",&x,&y);

        e[x].pb(y);e[y].pb(x);

    }

    for (int i=;i<=n;i++) if (e[i].size()==) bfs(i,root->c[a[i]]);

    build();

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

    return ;

}