#define MAXM 10010
#define INF 20000
using namespace std;
struct node
{
    int to, next;
} e[MAXM << 1];
int head[MAXM], tot;
int f[MAXM][3], m, n, c[MAXM];
void add(int u, int v)
{
    tot++, e[tot].to = v, e[tot].next = head[u], head[u] = tot;
}
void init()
{
    int i, u, v;
    scanf("%d%d", &m, &n);
    for (i = 1; i <= n; i++)
        scanf("%d", &c[i]);
    for (i = 1; i < m; i++)
    {
        scanf("%d%d", &u, &v);
        add(u, v), add(v, u);
    }
    for (i = 1; i <= m; i++)
        f[i][0] = f[i][1] = 1;
}
void dfs(int u, int fa)
{
    int i, v;
    for (i = head[u]; i; i = e[i].next)
    {
        v = e[i].to;
        if (v == fa)
            continue;
        dfs(v, u);
        if (v <= n)
            f[v][!c[v]] = INF, f[v][2] = 1;
        f[u][0] += min(f[v][2], min(f[v][0] - 1, f[v][1]));
        f[u][1] += min(f[v][2], min(f[v][0], f[v][1] - 1));
        f[u][2] += min(f[v][2], min(f[v][0], f[v][1]));
    }
}
int main()
{
    init();
    dfs(n + 1, -1);
    printf("%d\n", min(f[n + 1][2], min(f[n + 1][0], f[n + 1][1])));
    return 0;
}