How to get the build number from other build configuration (for example B) without increasing the B build number in Teamcity

Question

I have 2 build configuration named A and B.I want to use the build number of build config B in the build step of A. And I don't want a change to be made in the build number of B (that is, it won't be built again.) Only when the build number of B is changed, there is a real change in project B.

i tried snapshot dependency, but it doesn't work.