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#include<cstdio>
#include<cstring>
#include<algorithm>
#include<iostream>
#include<queue>
#include<map>
#include<stack>
#include<cmath>
#include<set>
#include<bitset>
#define inc(i,l,r) for(int i=l;i<=r;i++)
#define dec(i,l,r) for(int i=l;i>=r;i--)
#define link(x) for(edge *j=h[x];j;j=j->next)
#define mem(a) memset(a,0,sizeof(a))
#define ll long long
#define eps 1e-8
#define succ(x) (1<<x)
#define lowbit(x) (x&(-x))
#define sqr(x) ((x)*(x))
#define mid (x+y>>1)
#define NM 50005
#define nm 1024
#define pi 3.1415926535897931
using namespace std;
const ll inf=998244353;
ll read(){
ll x=0,f=1;char ch=getchar();
while(!isdigit(ch)){if(ch=='-')f=-1;ch=getchar();}
while(isdigit(ch))x=x*10+ch-'0',ch=getchar();
return f*x;
}
struct edge{int t;edge*next;}e[NM<<1],*h[NM],*o=e;
void add(int x,int y){o->t=y;o->next=h[x];h[x]=o++;}
int n,m,tot,a[NM],_x,_y;
unsigned short d[NM][nm];
ll ans[nm];
void dfs(int x,int f){
inc(i,0,tot)if(i&succ(a[x]-1))d[x][i]=1;else d[x][i]=0;
link(x)if(j->t!=f){
dfs(j->t,x);
inc(i,0,tot)ans[i]+=1ll*d[x][i]*d[j->t][i];
inc(i,0,tot)if(i&succ(a[x]-1))d[x][i]+=d[j->t][i];
}
}
int main(){
while(~scanf("%d%d",&n,&m)){
tot=succ(m)-1;mem(e);mem(h);mem(ans);o=e;
inc(i,1,n)a[i]=read();
inc(i,2,n){_x=read();_y=read();add(_x,_y);add(_y,_x);}
if(m==1){printf("%lld\n",1ll*n*n);continue;}
dfs(1,0);
ll s=0;
inc(i,0,tot)if((m-__builtin_popcount(i))&1)s-=ans[i];else s+=ans[i];
printf("%lld\n",s<<1);
}
return 0;
}
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