When I am using c++ mode to edit c++ sources, emacs always auto indent the class declarations inside a namespace. I don't want the auto indentation inside a namespace. How to turn off it?

Code example:
I want such style:

namespace foo {
class A {
};
}

emacs forces to:

namespace foo {
class A {
};
}

I have to delete the spaces in front of "class A" manually.

Greetings,

Zhongxing Xu