#include<cstdio>

#include<vector>

#include<cstring>

#define MAX 100010

using namespace std;

vector <int> a[MAX];

int visit[MAX];

int cat[MAX];

int leaf[MAX];

int ans,m;

void dfs(int x,int numcat)

{

    if(visit[x])

    return;

    else

    visit[x]=1;

    if(cat[x])

    numcat++;

    else

    numcat=0;

    if(numcat>m)

    return;

    if(leaf[x]==1&&x!=1)

    ans++;

    int len=a[x].size();

    for(int i=0;i<len;i++)

    dfs(a[x][i],numcat);

}

int main()

{

    int n,i,j,k,numcat;

    while(~scanf("%d%d",&n,&m))

    {

        numcat=ans=0;

        memset(visit,0,sizeof(visit));

        memset(leaf,0,sizeof(leaf));

        for(i=1;i<=n;i++)

        {

            scanf("%d",&cat[i]);

            a[i].clear();

        }

        for(i=1;i<=n-1;i++)

        {

            scanf("%d%d",&j,&k);

            a[j].push_back(k);

            a[k].push_back(j);

            leaf[j]++;

            leaf[k]++;

        }

        dfs(1,0);

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

    }

    return 0;

}