#include using namespace std; using lint = long long; using pi = array; #define sz(a) ((int)(a).size()) #define all(a) (a).begin(), (a).end() const int MAXN = 300005; const int mod = 998244353; const int inv2 = (mod + 1) / 2; struct mint { int val; mint() { val = 0; } mint(const lint &v) { val = (-mod <= v && v < mod) ? v : v % mod; if (val < 0) val += mod; } friend ostream &operator<<(ostream &os, const mint &a) { return os << a.val; } friend bool operator==(const mint &a, const mint &b) { return a.val == b.val; } friend bool operator!=(const mint &a, const mint &b) { return !(a == b); } friend bool operator<(const mint &a, const mint &b) { return a.val < b.val; } mint operator-() const { return mint(-val); } mint &operator+=(const mint &m) { if ((val += m.val) >= mod) val -= mod; return *this; } mint &operator-=(const mint &m) { if ((val -= m.val) < 0) val += mod; return *this; } mint &operator*=(const mint &m) { val = (lint)val * m.val % mod; return *this; } friend mint ipow(mint a, lint p) { mint ans = 1; for (; p; p /= 2, a *= a) if (p & 1) ans *= a; return ans; } mint inv() const { return ipow(*this, mod - 2); } mint &operator/=(const mint &m) { return (*this) *= m.inv(); } friend mint operator+(mint a, const mint &b) { return a += b; } friend mint operator-(mint a, const mint &b) { return a -= b; } friend mint operator*(mint a, const mint &b) { return a *= b; } friend mint operator/(mint a, const mint &b) { return a /= b; } operator int64_t() const { return val; } }; mint ret = 0; struct node { int j; mint A, S; bool operator<(const node &nd) const { return j < nd.j; } }; vector gph[MAXN]; int val[MAXN], sz[MAXN], n; mint pwr[MAXN]; vector merge(vector &a, vector &b) { int swp = 0; vector bisect(sz(a) + 1); int j = 0; for (int i = 0; i < sz(a); i++) { while (j < sz(b) && b[j].j < a[i].j) j++; bisect[i] = j; } bisect[sz(a)] = sz(b); mint tasum = 0, tssum = 0; mint asum = 0, ssum = 0; vector c; for (int i = 0; i < sz(a); i++) { for (int j = (i ? bisect[i - 1] : 0); j < bisect[i]; j++) { asum += b[j].A; ssum += b[j].S; } tasum += a[i].A; tssum += a[i].S; a[i].A = a[i].A * ssum + a[i].S * asum; a[i].S = a[i].S * ssum; for (int j = bisect[i]; j < bisect[i + 1]; j++) { auto cp = b[j]; cp.A = (tssum)*cp.A + tasum * cp.S; cp.S = (tssum)*cp.S; c.push_back(cp); } } vector nxt(sz(a) + sz(c)); merge(all(a), all(c), nxt.begin()); a.clear(); for (int i = 0; i < sz(nxt);) { int j = i; node toput; toput.j = nxt[i].j; while (j < sz(nxt) && nxt[i].j == nxt[j].j) { toput.A += nxt[j].A; toput.S += nxt[j].S; j++; } i = j; a.push_back(toput); } return a; } auto cmp = [](vector &a, vector &b) { return sz(a) > sz(b); }; vector dfs(int x, int p = -1) { vector a; sz[x] = 1; a.push_back((node){val[x], mint(1), mint(1)}); priority_queue, vector>, decltype(cmp)> pq(cmp); // max heap pq.push(a); for (auto &y : gph[x]) { if (y == p) continue; auto b = dfs(y, x); for (auto &bb : b) { ret += mint(bb.j) * bb.A * mint((mod + 1) / 2); bb.A *= mint(inv2); bb.S *= mint(inv2); } b.push_back({val[x], mint(0), mint(inv2)}); sort(all(b)); pq.push(b); sz[x] += sz[y]; } while (sz(pq) > 1) { auto x = pq.top(); pq.pop(); auto y = pq.top(); pq.pop(); pq.push(merge(x, y)); } return pq.top(); } int main() { ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0); cin >> n; pwr[0] = 1; for (int i = 0; i < n; i++) { pwr[i + 1] = pwr[i] * mint(2); cin >> val[i]; } for (int i = 0; i < n - 1; i++) { int u, v; cin >> u >> v; u--; v--; gph[u].push_back(v); gph[v].push_back(u); } auto ans = dfs(0); for (auto &z : ans) { ret += z.A * mint(z.j); } cout << ret * pwr[n - 1] << "\n"; }