IF YOU THINK you're having a bad day today,

imagine what it must be like to be a tween girl.

Zayn Malik said yesterday that he is leaving One Direction.

Has algebra ever seemed so pointless?

Zayn, who recently left the quintet's world tour to return home, was told by his boy-band mates that they "totally respect his decision and send him all our love for the future."

Zayn said in a statement that his time with One Direction "has been more than I could ever have imagined."

"But, after five years, I feel like it is now the right time for me to leave the band," he said. "I'd like to apologize to the fans if I've let anyone down, but I have to do what feels right in my heart.

"I am leaving because I want to be a normal 22-year-old who is able to relax and have some private time out of the spotlight."

One Direction said it would continue to tour with the four remaining members and would record a new album later this year.

As Four-Fifths Direction.

Philly 'Voice' update

Seeking an answer to what really happened to Philly street performer Anthony Riley on "The Voice," Philly.com's Nick Vadala spoke with Riley's spokesman, attorney Evan Shingles.

"Anthony indicated to me that he has some medical issues that would make it impossible for him to continue on 'The Voice,' " Shingles said. "What those are, I don't know."

Shingles, who represented Riley after the singer learned it wasn't such a wonderful world following his arrest in 2007 for singing Sam Cooke in Rittenhouse Square, also nixed the Internet rumors about Riley's departure.

Shingles said that Riley had no issue facing off against Mia Z on the show and that the pro-Mumia Abu-Jamal tweet wasn't even from Riley. Shingles said it was the work of a "disgruntled former manager" who took over Riley's Twitter account.

"Anthony is not professing any support for Mumia that I'm aware of," Shingles says. "He's never spoken with me about, and never professed to have, radical politics."

Shingles said he is pursuing the former manager with the hope of regaining control of Riley's social media.

TATTBITS

* Did all that boozing that takes place on "Mad Men" go to Jon Hamm's head?

Or liver?

The "Mad Men" star has completed treatment for alcohol addiction, his spokeswoman said.

Hamm had the support of his longtime partner, actress-filmmaker Jennifer Westfeldt, in his struggle, publicist Annett Wolf said in a statement.

The couple have asked "for privacy and sensitivity going forward," the statement said.

The disclosure, first reported by TMZ, came as the final season of the 1960s-set drama begins April 5 on AMC.

* The off-Broadway phenomenon "The Fantasticks" will end a record-breaking run of 20,672 performances, which started when Dwight D. Eisenhower was president.

Producers of the low-tech show said yesterday that the musical will close on May 3, the 55th anniversary of its opening in 1960.

How long until someone mounts a revival?

Ben E. King's "Stand by Me," has been selected for preservation at the Library of Congress, along with recordings from Joan Baez, the Righteous Brothers, Steve Martin and the darker sounds of the band Radiohead.

Twenty-five sound recordings, spanning from 1890 to 1999, were added yesterday to the library's National Recording Registry. Each year the library chooses recordings that are "culturally, historically or aesthetically significant."

Some of the unforgettable tunes being archived include

"Ac-Cent-Tchu-Ate the Positive" from Johnny Mercer, in 1944; Baez's first solo album; the Righteous Brothers' "You've Lost That Lovin' Feelin' "; and Steve Martin's "A Wild and Crazy Guy" comedy album, which broke new ground in the 1970s.

Upon hearing of his archive-worthy achievement, Martin deadpanned: "I could not be more proud of this honor. This means the record was probably funny."

The Library of Congress has been seeking to preserve important sound recordings for 15 years under terms of a preservation act passed by Congress.

If only Congress could figure out how to preserve the middle class.

- Daily News wire services

contributed to this report.

Email: gensleh@phillynews.com

Phone: 215-854-5678

On Twitter: @DNTattle