restructure zeta/** to storage/zeta/**

storage/zeta/cpp/completed/15552.cpp

@@ -0,0 +1,19 @@
+#include <iostream>
+
+using namespace std;
+
+int main() {
+
+    ios_base::sync_with_stdio(0);
+    cin.tie(nullptr);
+    int T;
+    int A, B;
+    std::cin >> T;
+
+    for (int i = 0; i < T; i++) {
+        std::cin >> A >> B;
+        std::cout << A + B << '\n';
+    }
+
+    return 0;
+}