Your error message says:
java.lang.ClassNotFoundException:
But the format of this message usually looks like this:
java.lang.ClassNotFoundException: SomeNonExistingClass
How comes that the name of the class that is not found is missing? Because you have an instruction in your example that refers to an empty class name (""). So you need to look for an instruction where you forgot to specify the class name. And that's here:
invokestatic printInt(I)V
Instead it should read:
invokestatic Output/printInt(I)V
this will fix your problem.