who is this second person mentioned?
Karl Martin Sandberg, known professionally as Max Martin, is a Swedish singer, songwriter, and record producer
Max Martin
Karl Martin Sandberg (; born 26 February 1971), known professionally as Max Martin, is a Swedish singer, songwriter, and record producer
who wrote shake it off by taylor swift Taylor Swift, Max Martin and Shellback.
wiki:13083666
Max Martin [SEP] Introduction
Karl Martin Sandberg (; born 26 February 1971), known professionally as Max Martin, is a Swedish singer, songwriter, and record producer. He rose to prominence in the late 1990s after making a string of hit singles such as Britney Spears' "...Baby One More Time" (1998), the Backstreet Boys' "I Want It That Way" (1999), and NSYNC's "It's Gonna Be Me" (2000). Martin has written or co-written 23 "Billboard" Hot 100 number-one songs, most of which he has also produced or co-produced, including Katy Perry's "I Kissed a Girl" (2008), Maroon 5's "One More Night" (2012), Taylor Swift's "Shake It Off" and "Blank Space" (2014), and The Weeknd's "Blinding Lights" (2019).