Tracking inactivity with a report

Tracking inactivity with a report

We have defined "leads" not very strict, which means that leads could be "not yet contacted" or "contacted" but not yet a prospect or "lost". Now I want to create a report where I can track the "leads" where no action (call or mail) has been taken so far and where action has been taken.

Can someone give me a solution to create a report where I can make a list of "inactive" leads? Thanks in advance.