diff --git a/HDOJ/2024.cpp b/HDOJ/2024.cpp
new file mode 100644
index 0000000..0a78ebf
--- /dev/null
+++ b/HDOJ/2024.cpp
@@ -0,0 +1,60 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <queue>
+#include <algorithm>
+
+#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;
+
+char line[1024];
+
+int main()
+{
+    //cout<<"Hello World!"<<endl;
+    int n;
+    scanf("%d%*c",&n);
+    for(int i=0;i<n;i++)
+    {
+        gets(line);
+        if(!((line[0]>='A'&&line[0]<='Z')||(line[0]>='a'&&line[0]<='z')||(line[0]=='_')))
+        {
+            printf("no\n");
+            continue;
+        }
+
+        int len=strlen(line);
+        bool done=false;
+
+        for(int j=1;j<len;j++)
+        {
+            if(!(
+                 (line[j]>='A'&&line[j]<='Z')||
+                 (line[j]>='a'&&line[j]<='z')||
+                 (line[j]=='_')||
+                 (line[j]>='0'&&line[j]<='9')
+                ))
+            {
+                printf("no\n");
+                done=true;
+                break;
+            }
+        }
+
+        if(!done)
+        {
+            printf("yes\n");
+        }
+    }
+
+    return 0;
+}