diff --git a/Luogu/P8818/P8818.cpp b/Luogu/P8818/P8818.cpp
new file mode 100644
index 00000000..5ef34433
--- /dev/null
+++ b/Luogu/P8818/P8818.cpp
@@ -0,0 +1,169 @@
+#include <iostream>
+
+using std::cin;
+using std::cout;
+const char endl = '\n';
+
+const int N = 1e5 + 5;
+const long long INF = 0x3f3f3f3f3f3f3f3f;
+
+int n, m, q;
+long long a[N], b[N];
+
+struct node {
+    int l, r, cnt;
+    long long min, max;
+
+    node(int _l = 0, int _r = 0)
+        : l(_l), r(_r), cnt(0), min(INF), max(-INF) {}
+} tr1a[N << 2], tr1b[N << 2], tr2a[N << 2], tr2b[N << 2];
+
+void pushup(node* tr, int u) {
+    tr[u].cnt = tr[u << 1].cnt + tr[u << 1 | 1].cnt;
+    tr[u].min = std::min(tr[u << 1].min, tr[u << 1 | 1].min);
+    tr[u].max = std::max(tr[u << 1].max, tr[u << 1 | 1].max);
+}
+
+void build1(node* tr, long long* a, int u, int l, int r) {
+    tr[u] = node(l, r);
+
+    if (l == r) {
+        if (a[l] >= 0) {
+            tr[u].max = tr[u].min = a[l];
+            tr[u].cnt = 1;
+        }
+
+        return;
+    }
+
+    int mid = l + r >> 1;
+
+    build1(tr, a, u << 1, l, mid);
+    build1(tr, a, u << 1 | 1, mid + 1, r);
+
+    pushup(tr, u);
+}
+
+void build2(node* tr, long long* a, int u, int l, int r) {
+    tr[u] = node(l, r);
+
+    if (l == r) {
+        if (a[l] <= 0) {
+            tr[u].max = tr[u].min = a[l];
+            tr[u].cnt = 1;
+        }
+
+        return;
+    }
+
+    int mid = l + r >> 1;
+
+    build2(tr, a, u << 1, l, mid);
+    build2(tr, a, u << 1 | 1, mid + 1, r);
+
+    pushup(tr, u);
+}
+
+long long query_min(node* tr, int u, int l, int r) {
+    if (l <= tr[u].l && tr[u].r <= r) return tr[u].min;
+
+    int mid = tr[u].l + tr[u].r >> 1;
+    long long res = INF;
+
+    if (l <= mid) res = std::min(res, query_min(tr, u << 1, l, r));
+    if (r > mid) res = std::min(res, query_min(tr, u << 1 | 1, l, r));
+
+    return res;
+}
+
+long long query_max(node* tr, int u, int l, int r) {
+    if (l <= tr[u].l && tr[u].r <= r) return tr[u].max;
+
+    int mid = tr[u].l + tr[u].r >> 1;
+    long long res = -INF;
+
+    if (l <= mid) res = std::max(res, query_max(tr, u << 1, l, r));
+    if (r > mid) res = std::max(res, query_max(tr, u << 1 | 1, l, r));
+
+    return res;
+}
+
+int query_cnt(node* tr, int u, int l, int r) {
+    if (l <= tr[u].l && tr[u].r <= r) return tr[u].cnt;
+
+    int mid = tr[u].l + tr[u].r >> 1;
+    int cnt = 0;
+
+    if (l <= mid) cnt += query_cnt(tr, u << 1, l, r);
+    if (r > mid) cnt += query_cnt(tr, u << 1 | 1, l, r);
+
+    return cnt;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin.tie(nullptr);
+
+    cin >> n >> m >> q;
+
+    for (int i = 1; i <= n; i++) {
+        cin >> a[i];
+    }
+
+    for (int i = 1; i <= m; i++) {
+        cin >> b[i];
+    }
+
+    build1(tr1a, a, 1, 1, n);
+    build2(tr1b, a, 1, 1, n);
+    build1(tr2a, b, 1, 1, m);
+    build2(tr2b, b, 1, 1, m);
+
+    while (q--) {
+        int l1, r1, l2, r2;
+
+        cin >> l1 >> r1 >> l2 >> r2;
+
+        long long max_1a = query_max(tr1a, 1, l1, r1),
+                  min_1a = query_min(tr1a, 1, l1, r1);
+        long long max_1b = query_max(tr1b, 1, l1, r1),
+                  min_1b = query_min(tr1b, 1, l1, r1);
+        long long max_2a = query_max(tr2a, 1, l2, r2),
+                  min_2a = query_min(tr2a, 1, l2, r2);
+        long long max_2b = query_max(tr2b, 1, l2, r2),
+                  min_2b = query_min(tr2b, 1, l2, r2);
+
+        int cnt_1a = query_cnt(tr1a, 1, l1, r1),
+            cnt_1b = query_cnt(tr1b, 1, l1, r1);
+        int cnt_2a = query_cnt(tr2a, 1, l2, r2),
+            cnt_2b = query_cnt(tr2b, 1, l2, r2);
+
+        if (!cnt_1a) {      // 1. [l1, r1] 间无正数
+            if (!cnt_2a) {  // a. [l2, r2] 间无正数
+                cout << min_1b * max_2b << endl;
+            } else if (!cnt_2b) {  // b [l2, r2] 间无负数
+                cout << max_1b * max_2a << endl;
+            } else {
+                cout << max_1b * max_2a << endl;
+            }
+        } else if (!cnt_1b) {  // 2. [l1, r1] 间无负数
+            if (!cnt_2a) {     // a. [l2, r2] 间无正数
+                cout << min_1a * min_2b << endl;
+            } else if (!cnt_2b) {  // b [l2, r2] 间无负数
+                cout << max_1a * min_2a << endl;
+            } else {
+                cout << min_1a * min_2b << endl;
+            }
+        } else {
+            if (!cnt_2a) {  // a. [l2, r2] 间无正数
+                cout << min_1b * max_2b << endl;
+            } else if (!cnt_2b) {  // b [l2, r2] 间无负数
+                cout << max_1a * min_2a << endl;
+            } else {
+                cout << std::max(max_1b * max_2a, min_1a * min_2b) << endl;
+            }
+        }
+    }
+
+    return 0;
+}