#include <bits/stdc++.h>
using namespace std;
template <typename A>
ostream& operator<<(ostream& cout, vector<A> const& v);
template <typename A, typename B>
ostream& operator<<(ostream& cout, pair<A, B> const& p) {
  return cout << "(" << p.first << ", " << p.second << ")";
}
template <typename A>
ostream& operator<<(ostream& cout, vector<A> const& v) {
  cout << "[";
  for (int i = 0; i < v.size(); i++) {
    if (i) cout << ", ";
    cout << v[i];
  }
  return cout << "]";
}
template <typename A, typename B>
istream& operator>>(istream& cin, pair<A, B>& p) {
  cin >> p.first;
  return cin >> p.second;
}
mt19937_64 rng(std::chrono::steady_clock::now().time_since_epoch().count());
void usaco(string filename) {
  freopen((filename + ".in").c_str(), "r", stdin);
  freopen((filename + ".out").c_str(), "w", stdout);
}
const long double pi = 3.14159265358979323846;
struct segtree {
  int n, depth;
  vector<long long> tree, lazy;
  void init(int second, long long* arr) {
    n = second;
    tree = vector<long long>(4 * second, 0);
    lazy = vector<long long>(4 * second, 0);
    init(0, 0, n - 1, arr);
  }
  long long init(int i, int l, int r, long long* arr) {
    if (l == r) return tree[i] = arr[l];
    int mid = (l + r) / 2;
    long long a = init(2 * i + 1, l, mid, arr),
              b = init(2 * i + 2, mid + 1, r, arr);
    return tree[i] = a > b ? a : b;
  }
  void update(int l, int r, long long v) { update(0, 0, n - 1, l, r, v); }
  long long update(int i, int tl, int tr, int ql, int qr, long long v) {
    eval_lazy(i, tl, tr);
    if (tr < ql || qr < tl) return tree[i];
    if (ql <= tl && tr <= qr) {
      lazy[i] += v;
      eval_lazy(i, tl, tr);
      return tree[i];
    }
    int mid = (tl + tr) / 2;
    long long a = update(2 * i + 1, tl, mid, ql, qr, v),
              b = update(2 * i + 2, mid + 1, tr, ql, qr, v);
    return tree[i] = a > b ? a : b;
  }
  long long query(int l, int r) { return query(0, 0, n - 1, l, r); }
  long long query(int i, int tl, int tr, int ql, int qr) {
    eval_lazy(i, tl, tr);
    if (ql <= tl && tr <= qr) return tree[i];
    if (tr < ql || qr < tl) return 1e13;
    int mid = (tl + tr) / 2;
    long long a = query(2 * i + 1, tl, mid, ql, qr),
              b = query(2 * i + 2, mid + 1, tr, ql, qr);
    return a > b ? a : b;
  }
  void eval_lazy(int i, int l, int r) {
    tree[i] += lazy[i];
    if (l != r) {
      lazy[i * 2 + 1] += lazy[i];
      lazy[i * 2 + 2] += lazy[i];
    }
    lazy[i] = 0;
  }
};
long long n, m, q, k, l, r, x, y, z;
const long long template_array_size = 1e6 + 16318;
long long a[template_array_size];
long long b[template_array_size];
long long c[template_array_size];
string second, t;
long long ans = 0;
vector<long long> edges[500005];
vector<long long> ch[500005];
long long val[500005];
long long val2[500005];
long long vl[500005];
long long dep[500005];
bool can[500005];
segtree st;
bool cval(long long a, long long b) {
  if (val[a] == val[b]) return dep[a] < dep[b];
  return val[a] > val[b];
}
void setv(long long v, long long p, long long va, long long d = 0) {
  val[v] = va;
  dep[v] = d;
  for (long long x : edges[v]) {
    if (x != p) {
      ch[v].push_back(x);
      setv(x, v, min(va, a[x]), d + 1);
    }
  }
}
void add(long long val, long long x) {
  long long lv = 0, rv = k;
  while (lv < rv) {
    long long mv = (lv + rv) / 2;
    if (b[mv] > val)
      lv = mv + 1;
    else
      rv = mv;
  }
  if (lv < k) st.update(lv, k - 1, x);
}
vector<long long> cur;
long long tsz = 0;
void checkv(long long v, long long va) {
  val2[v] = va;
  cur.push_back(v);
  for (long long x : ch[v]) {
    checkv(x, min(va, a[x]));
  }
}
bool check(long long v, long long t) {
  cur.clear();
  checkv(v, t);
  tsz += cur.size();
  for (long long x : cur) {
    add(val[x], 1);
    add(val2[x], -1);
  }
  bool pos = (st.query(0, k - 1) <= 0);
  for (long long x : cur) {
    add(val2[x], 1);
    add(val[x], -1);
  }
  return pos;
}
void solve(int tc = 0) {
  cin >> n;
  for (long long i = 0; i < n; i++) cin >> a[i];
  for (long long i = 0; i < n - 1; i++) {
    cin >> x >> y;
    --x;
    --y;
    edges[x].push_back(y);
    edges[y].push_back(x);
  }
  setv(0, -1, a[0]);
  cin >> k;
  for (long long i = 0; i < k; i++) cin >> b[i];
  sort(b, b + k);
  reverse(b, b + k);
  iota(c, c + k, 1);
  st.init(k, c);
  for (long long i = 0; i < n; i++) add(val[i], -1);
  iota(vl, vl + n, 0);
  sort(vl, vl + n, cval);
  long long sent = 1e17;
  long long ans = sent;
  can[0] = 1;
  bool pos = 1;
  for (long long i = 0; i < k; i++) {
    long long x = vl[i];
    if (val[x] >= b[i]) {
      for (long long y : ch[x]) can[y] = 1;
      can[x] = 0;
    } else {
      pos = 0;
      for (long long j = 0; j < n; j++) {
        if (can[j]) {
          if (check(j, b[i])) {
            ans = min(ans, b[i] - val[j]);
          }
        }
      }
      break;
    }
  }
  if (pos) ans = 0;
  if (ans == sent) ans = -1;
  cout << ans << '\n';
}
int main() {
  { ios_base::sync_with_stdio(false); }
  { cin.tie(NULL); }
  cout << setprecision(15) << fixed;
  int tc = 1;
  for (int t = 0; t < tc; t++) solve(t);
}
