diff --git a/HDOJ/2042.cpp b/HDOJ/2042.cpp
new file mode 100644
index 0000000..a439d00
--- /dev/null
+++ b/HDOJ/2042.cpp
@@ -0,0 +1,37 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <queue>
+#include <stack>
+#include <algorithm>
+#include <sstream>
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+/// This Contest and Compile does not support C++11.
+//#include <thread>
+//#include <mutex>
+//#include <condition_variable>
+//#include <functional>
+
+using namespace std;
+
+int main()
+{
+    int n;
+    cin>>n;
+    for(int i=0;i<n;i++)
+    {
+        int a;
+        cin>>a;
+        int cc=3;
+        while(a--)
+        {
+            cc=(cc-1)*2;
+        }
+        cout<<cc<<endl;
+    }
+    return 0;
+}