View Compilation Error

0_0_33308950_11564.cs(18,5): error CS0246: The type or namespace name 'IntPtr' could not be found (are you missing a using directive or an assembly reference?)
0_0_33308950_11564.cs(23,5): error CS0246: The type or namespace name 'ShowWindowCommands' could not be found (are you missing a using directive or an assembly reference?)
0_0_33308950_11564.cs(17,22): error CS0246: The type or namespace name 'IntPtr' could not be found (are you missing a using directive or an assembly reference?)
0_0_33308950_11564.cs(16,2): error CS0246: The type or namespace name 'DllImport' could not be found (are you missing a using directive or an assembly reference?)
0_0_33308950_11564.cs(16,2): error CS0246: The type or namespace name 'DllImportAttribute' could not be found (are you missing a using directive or an assembly reference?)