HBO’s Last Week Tonight star John Oliver told Stephen Colbert tonight he has zero interest in Donald Trump when Colbert confessed he’d started talking about the GOP front-runner within 30 seconds of taking over David Letterman’s late-night show.

“I couldn’t give less of a f–k. It’s physically impossible,” Oliver said of the real estate mogul/reality TV star turned candidate, and the presidential race, as Colbert’s guest. Colbert had brought it up almost immediately, having dined on his favorite subject nightly since debuting at The Late Show host. “It’s the 2016 election and it’s 2015 right now…I don’t care until we are in the same year as the thing I am supposed to care about.” In fact, Oliver added, he’d prefer to talk about anything not election related, adding, “There are plenty of problems in the world.”

“They are sad,” Colbert complained. “Meanwhile – his hair!”

Pointing out Oliver’s show each week does a deep dive into just one subject, on which he often speaks for up to 18 minutes, Colbert read some topics suggested by Oliver fans:  saving coral reefs and bear hunting season.

“If they’re suggesting coral reefs, those are people who want the show to end,” Oliver shot back, adding, “We don’t take suggestions from people.”

“Really? You have a site. You have a place on your site for suggestions,” Colbert corrected, noting that’s where he got the list of suggestions.

“I genuinely did not know we have a web site,” Oliver confessed.

The two former The Daily Show correspondents, both of whom slipped through Comedy Central’s fingers when wooed by other networks, mourned the loss of their mentor Jon Stewart on late-night TV. Colbert wondered if Oliver missed Stewart on air as much as he does.

“I miss him hugely,” Oliver said.

But, Colbert added generously, he thought Stewart’s replacement, Trevor Noah “crushed it.” Oliver did that one better, saying Noah gets credit for “taking on the impossible” adding “you can’t replace the irreplaceable.”

“I wouldn’t know what that’s like,” snarked Colbert, by way of reminding Oliver he’s replaced Letterman on CBS.