1 #include<cstdio>
 2 #include<iostream>
 3 using namespace std;
 4 const int inf=1000000000;
 5 int n,m,c[100010],f[100010][2],to[200010],from[200010],head[100010],cnt;
 6 void insert(int x,int y) { to[++cnt]=y; from[cnt]=head[x]; head[x]=cnt; }
 7 void dp(int root,int fa)
 8 {
 9     f[root][0]=f[root][1]=1;
10     if (root<=m) if (c[root]) f[root][0]=inf; else f[root][1]=inf;
11     for (int i=head[root];i;i=from[i])
12         if (to[i]!=fa)
13         {
14             dp(to[i],root);
15             f[root][0]+=min(f[to[i]][0]-1,f[to[i]][1]);
16             f[root][1]+=min(f[to[i]][1]-1,f[to[i]][0]);
17         }
18 }
19 int main()
20 {
21     scanf("%d%d",&n,&m);
22     for (int i=1;i<=m;i++) scanf("%d",&c[i]);
23     for (int i=1;i<=n-1;i++)
24     {
25         int x,y;
26         scanf("%d%d",&x,&y);
27         insert(x,y);
28         insert(y,x);
29     }
30     dp(m+1,-1);
31     printf("%d",min(f[m+1][1],f[m+1][0]));
32     return 0;
33 }