install xpdf-common planner regina3-dev isdnutils-doc mailagent Reading package lists... Building dependency tree... Reading state information... Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming. The following information may help to resolve the situation: The following packages have unmet dependencies: regina3-dev : Depends: libc6-dev but it is not going to be installed E: Broken packages