Question: Which series did Kim Ji-won star in first, Gap-dong or The Heirs?

Context paragraphs:
Secret (TV series): Secret ( is a South Korean television series starring Kim Ha-neul, Ha Ji-won, Ryu Si-won and Kim Min-jong.  It aired on MBC from September 13 to November 9 on Wednesdays and Thursdays at 21:00 for 18 episodes.

Gap-dong: Gap-dong () is a 2014 South Korean television series starring Yoon Sang-hyun, Sung Dong-il, Kim Min-jung, Kim Ji-won and Lee Joon.  It aired on cable channel tvN from April 11 to June 14, 2014 on Fridays and Saturdays at 20:40 for 20 episodes.

What's Up (TV series): What's Up () is a 2011 South Korean television series starring Lim Ju-hwan, Daesung, Lim Ju-eun, Oh Man-seok, Jang Hee-jin, Lee Soo-hyuk, Kim Ji-won and Jo Jung-suk.  It aired on MBN on Saturdays to Sundays at 23:00 for 20 episodes beginning December 3, 2011.

Kim Ji-won (boxer): Kim Ji-won (Hangul: 김지원, Hanja: 金知元; born 6 August 1959 in Seoul) is a former South Korean boxer who was an unbeaten world champion in the super bantamweight division.

Fight for My Way: Fight for My Way (; lit.  "Third-Rate My Way") is a South Korean television series starring Park Seo-joon and Kim Ji-won, with Ahn Jae-hong and Song Ha-yoon.  It premiered on May 22, 2017 every Monday and Tuesday at 22:00 (KST) on KBS2.

Kim Ji-won (badminton): Kim Ji-won (Hangul: 김지원; born 26 February 1995) is a South Korean female badminton player.  In 2013, Kim and her national teammates won the Suhadinata Cup after beat Indonesian junior team in the final round of the mixed team event.  She also won the girls' doubles title partnered with Chae Yoo-jung.

Bobby (rapper): Kim Ji-won (Hangul: 김지원 ; born December 21, 1995), better known by his stage name Bobby (Hangul: 바비 ) is a Korean-American rapper and singer.  He is known as a member of the popular South Korean boy group iKON, signed under YG Entertainment.

Descendants of the Sun: Descendants of the Sun () is a 2016 South Korean television series starring Song Joong-ki, Song Hye-kyo, Jin Goo, and Kim Ji-won.  It aired on KBS2 from February 24 to April 14, 2016, on Wednesdays and Thursdays at 22:00 for 16 episodes.  KBS then aired three additional special episodes from April 20 to April 22, 2016 containing highlights and the best scenes from the series, the drama's production process, behind-the-scenes footage, commentaries from cast members and the final epilogue.

2016 KBS Drama Awards: The 2016 KBS Drama Awards (), presented by Korean Broadcasting System (KBS), was held on December 31, 2016 at KBS Hall in Yeouido, Seoul.  It was hosted by Jun Hyun-moo, Park Bo-gum and Kim Ji-won.

Kim Ji-won (actress): Kim Ji-won (Hangul: 김지원 ; Hanja: 金智媛 ; born October 19, 1992) is a South Korean actress.  She gained attention through her roles in television series "The Heirs" (2013), "Descendants of the Sun" (2016) and "Fight for My Way" (2017).

Supporting paragraphs: Gap-dong Kim Ji-won (actress)
Answer: The Heirs