diff --git a/S2OJ/14/14.cpp b/S2OJ/14/14.cpp
new file mode 100644
index 00000000..aa2318c7
--- /dev/null
+++ b/S2OJ/14/14.cpp
@@ -0,0 +1,91 @@
+#pragma GCC optimize("Ofast")
+
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, l, r, cntl, cntr;
+char op;
+long long x, c1[300005], c2[300005];
+
+inline int lowbit(int x) {
+    return x & -x;
+}
+
+inline void add1(int pos, long long x) {
+    while (pos <= n) {
+        c1[pos] += x;
+        pos += lowbit(pos);
+    }
+}
+
+inline void add2(int pos, long long x) {
+    while (pos <= n) {
+        c2[pos] += x;
+        pos += lowbit(pos);
+    }
+}
+
+inline long long query1(int pos) {
+    long long ret = 0;
+    while (pos) {
+        ret += c1[pos];
+        pos -= lowbit(pos);
+    }
+    return ret;
+}
+
+inline long long query2(int pos) {
+    long long ret = 0;
+    while (pos) {
+        ret += c2[pos];
+        pos -= lowbit(pos);
+    }
+    return ret;
+}
+
+int main() {
+    std::ios::sync_with_stdio(false);
+    cin >> n;
+    for (int i = 0; i < n; i++) {
+        cin >> op;
+        if (op == 'I') {
+            cin >> x;
+            add1(++cntl, x);
+        } else if (op == 'D') {
+            x = query1(cntl) - query1(cntl - 1);
+            add1(cntl--, -x);
+        } else if (op == 'L') {
+            if (cntl > 0) {
+                x = query1(cntl) - query1(cntl - 1);
+                add1(cntl--, -x);
+                add2(++cntr, x);
+            }
+        } else if (op == 'R') {
+            if (cntr > 0) {
+                x = query2(cntr) - query2(cntr - 1);
+                add2(cntr--, -x);
+                add1(++cntl, x);
+            }
+        } else if (op == 'Q') {
+            cin >> l >> r;
+            if (r <= cntl) {
+                cout << query1(r) - query1(l - 1) << endl;
+            } else if (l > cntl) {
+                cout << query2(cntl + cntr - l + 1) - query2(cntl + cntr - r) << endl;
+            } else {
+                cout << query1(cntl) - query1(l - 1) + query2(cntr) - query2(cntl + cntr - r) << endl;
+            }
+        } else if (op == 'C') {
+            cin >> l >> x;
+            if (l <= cntl) {
+                r = query1(l) - query1(l - 1);
+                add1(l, x - r);
+            } else {
+                r = query2(cntl + cntr - l + 1) - query2(cntl + cntr - l);
+                add2(cntl + cntr - l + 1, x - r);
+            }
+        }
+    }
+    return 0;
+}