According to Imam Abu Hanifah's precautionary position stated in the matn, if a dead animal is found un-swollen and its time of death is unknown, how far back is the well treated as impure?

Well Purification: Required Bucket Counts and Unknown Time of Death

• From 3 days and 3 nights ago.
• From 1 day and 1 night (24 hours) ago.
• Only from the exact moment of discovery.
• From 10 days ago.