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

storage/zeta/cpp/completed/2744.cpp

@@ -0,0 +1,19 @@
+#include <iostream>
+
+using namespace std;
+
+int main() {
+    string s;
+    cin >> s;
+    for (int i = 0; i < s.length(); i++) {
+        char c = s[i];
+        if (65 <= c && c <= 90) {
+            s[i] += 32;
+        } else {
+            s[i] -= 32;
+        }
+    }
+    cout << s;
+
+    return 0;
+}