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KNOW IT ALL: Monday's Top Stories at NBC News

From the final day to sign up for healthcare deadline to the Final Four, see the stories we're following.

Good morning, and happy Monday. Here are six of the top stories we are following this morning at NBC News:

1. Are you signed up? Healthcare enrollment deadline at midnight

At least two million people have signed up for healthcare in the last month, and more are expected to enroll on Monday in order to beat the deadline — and avoid the penalty. The administration is wise to hope that those procrastinators are young and healthy, so they’ll pay premiums without making much use of medical care. Read more in HEALTH.

2. Washington mudslide death toll hits 21

After more than a week of digging through mud and debris, searchers have confirmed 21 people were killed by the mudslide that washed over a square mile of Washington state last Saturday. Four more bodies were found but had not been identified, so they are not included in the death count. Another 30 people are still considered missing or unaccounted for — a number that was as high as 176 earlier in the rescue operation. Read more in NEWS.

3. Malaysia and Australia not giving up on search for jet

Malaysia's acting transport minister vowed Monday not to give up on the search for Flight MH370, which went missing March 8. Australian Prime Minister Tony Abbott had a similar message Sunday night, saying: "We can keep searching for quite some time to come, and we will keep searching for quite some time to come." Both leaders say they owe it to the families of the passengers to continue the search-effort. Read more in NEWS.

4. Final Four set after wild weekend

Another exciting weekend of March Madness has set up the Final Four — with only one No. 1 seed left standing. Now that brackets are thoroughly demolished, everyone can sit back and enjoy Florida vs. UConn and Wisconsin Vs. Kentucky on Saturday. Read more in SPORTS

UConn sent apologies to the White House, who's Hoops Fan in Chief picked Michigan State to go all the way.

5. A not-so-peaceful protest erupts in New Mexico

Crowds in Albuquerque gathered to protest what they say is an inordinate amount of shootings by police in the city. The protest was slated to be a peaceful one, but demonstrators threw rocks and police responded with tear gas. Twenty-three people have been shot in the city by police since 2012, according to the Associated Press. Read more in NEWS.

6. North Korea fires 500 shells, South Korea fires at them with 300

North Korea faxed — yes, faxed — South Korea to warn the South they would be conducting military drills. In response, the South returned more than 300 shots and dispatched F-15K fighter jets. About 100 of North Korea's shells landed in water near the sea border off the peninsula's western coast, which North Korea has never recognized. Read more in NEWS.

... What's trending today?

Plenty of people are going to miss the chemistry among the cast of How I Met Your Mother after the series concludes tonight. But Neil Patrick Harris and Jason Segel made their departure up to fans (slightly) on Inside the Actor's Studio" by spontaneously crooning "Confrontation" from Les Miserables.