add src folder

Author: nguyen-duc-dat

src/Main.java

@@ -0,0 +1,7 @@
+//TIP To <b>Run</b> code, press <shortcut actionId="Run"/> or
+// click the <icon src="AllIcons.Actions.Execute"/> icon in the gutter.
+public class Main {
+    public static void main(String[] args) {
+        System.out.print("Hello and welcome!");
+    }
+}