Greenoïd #3 - An alternative reality

Mission

You set off in search of the robot through brambles and giant ferns. By tracing its movements, you come to a small clearing. There, behind a large root, you spot a secret passageway that leads underground. Without hesitating for a second, you rush inside and stumble upon a huge underground base. What you see there leaves you speechless for several minutes. In front of you, hundreds of machines and robots are working in a frenzied atmosphere. The acronym ‘Assistance Universelle de Réhabilitation de l'Atmosphère’ scrolls across the screens on the walls, and a worrying countdown shows that there are less than two hours to go before… But before what?

You notice a computer in a discreet corner of the room. Scanning its data, you realise that AURA is in fact an artificial intelligence created thousands of years ago to protect nature and humanity. Always active, it monitors and protects the balance of Greenoïd. So why is her system on alert? Could it have been corrupted by a malicious program? In the computer files, you'll find a repository detailing the various robot commands. They activate as if preparing to wage war. You need to find out what's going on, and fast.

Rules

A computer provides a register of the robots in the base.

Each robot is set a specific task, designated by a letter:

C = CREATE

H = HEAL

P = PRESERVE

D = DESTROY

This gives a list of robots of this type: HPDHDCDHDHDCHCPDDDDDDHCDCPHDHHDP

You need to return the operation that occurs most frequently and the number of associated robots, separated by a ‘_’, for example ‘CREATE_56’ or ‘HEAL_49’.