sudo apt-get upgrade

aamir@aamir-pc:~$ sudo apt-get upgrade
Reading package lists... Done
Building dependency tree
Reading state information... Done
You might want to run 'apt-get -f install' to correct these.
The following packages have unmet dependencies:
 network-manager-openvpn : Depends: libnm-glib2 (>= 0.8~a~git.20090917t210753.fdb5ef2) but it is not installable
 network-manager-openvpn-gnome : Depends: libnm-glib2 (>= 0.8~a~git.20090917t210753.fdb5ef2) but it is not installable
E: Unmet dependencies. Try using -f.
aamir@aamir-pc:~$