Question: In which county is the city Ian Sharman is associated with located?

full_context: Document 1: Richmond Medical Center: Richmond Medical Center also known as Kaiser Richmond, Kaiser Foundation Hospital Richmond and RMC, is a large Kaiser Permanente hospital in downtown Richmond, California which serves 77,000 members registered under its medical plans. It opened in 1995 replacing the historic 1942 Richmond Field Hospital that serviced Liberty shipyard workers and thus gave birth to the HMO. However it was deemed seismically unsafe and this new campus was built.
Document 2: Suisun people: The Suisunes (also called the Suisun and the "People of the West Wind") were a tribe of Native Americans that lived in Northern California's Suisun Marsh regions of Solano County, California between what is now Suisun City, Vacaville and Putah Creek around 200 years ago. The Suisunes' main village, Yulyul, is believed to be where Rockville, California is located today. Father Abella, visitor to the tribe in 1811, indicated they resided in the present location of Fairfield, north of the Suisun Bay. One of the Suisunes' primary food sources was acorns. Their diet also included fish as well as miner's lettuce. Their huts (as recorded by the Spaniards in 1817) were conical wikiups made of rushes or tule thatch.
Document 3: John Muir Health: John Muir Health is a health care service headquartered in Walnut Creek, California and serving Contra Costa County, California and surrounding communities. It was formed in 1997 from the merger of John Muir Medical Center and Mt. Diablo Medical Center.
Document 4: Takeshi So: He currently trains marathon runner and 2016 Olympics hopeful Satoru Sasaki and runs the marathon program for the Japan Association of Athletics Federations.
Document 5: Cyprus: Tennis player Marcos Baghdatis was ranked 8th in the world, was a finalist at the Australian Open, and reached the Wimbledon semi-final, all in 2006. High jumper Kyriakos Ioannou achieved a jump of 2.35 m at the 11th IAAF World Championships in Athletics in Osaka, Japan, in 2007, winning the bronze medal. He has been ranked third in the world. In motorsports, Tio Ellinas is a successful race car driver, currently racing in the GP3 Series for Marussia Manor Motorsport. There is also mixed martial artist Costas Philippou, who competes in the Ultimate Fighting Championship promotion's middleweight division. Costas holds a 6-3 record in UFC bouts, and recently defeated "The Monsoon" Lorenz Larkin with a Knockout in the 1st round.
Document 6: Muir Beach, California: Muir Beach is a census designated place (CDP), unincorporated community, and beach that is located northwest of San Francisco in western Marin County, California, United States. It is named for John Muir. The population was 310 at the 2010 census. The community itself flanks the northwest side of the beach.
Document 7: Ian Sharman: Ian Sharman, born 30 August 1980, is a British ultramarathon runner, coach, and blogger for iRunFar living in Walnut Creek, CA. He currently holds the record for the Grand Slam of Ultrarunning and is the winner of the 2013, 2015, 2016 and 2017 Leadville Trail 100. He holds 9 Guinness Book of World's records for running marathons in costumes in the fastest time.
Document 8: Stefaan Engels: Stefaan Engels (born 7 April 1961, Ghent, Belgium), also known as "marathon man", is a Belgian marathoner and triathlete, the first man to run the marathon distance 365 consecutive times in a single year. He also holds the record for the most Ironman Triathlons in a year with 20 over 2007 and 2008.
Document 9: Chris Sharma: Chris Omprakash Sharma (born April 23, 1981) is an American rock climber. In 2007, NPR wrote that Sharma was considered the world's best rock climber. He is known for being the world's first climber to redpoint a route ("Jumbo love", 2008) and the second to climb a and a route (respectively, "Realization" in 2001 and "La Dura Dura" in 2013). He is also known for climbing the world's first and deep-water solo routes ("Es Pontàs" in 2007 and "Alasha" in 2017). He bolted and first ascended many of the hardest lines of the Catalonia region in Spain. In 2015, he opened the gym Sharma Climbing BCN in Barcelona. In 2019 he plans to open Europe's largest climbing gym in Madrid, Spain.
Document 10: Namibia: Inline hockey was first played in 1995 and has also become more and more popular in the last years. The Women's inline hockey National Team participated in the 2008 FIRS World Championships. Namibia is the home for one of the toughest footraces in the world, the Namibian ultra marathon. The most famous athlete from Namibia is Frankie Fredericks, sprinter (100 and 200 m). He won four Olympic silver medals (1992, 1996) and also has medals from several World Athletics Championships. He is also known for humanitarian activities in Namibia and beyond.
Document 11: John Muir: John Muir (/ mjʊər /; April 21, 1838 -- December 24, 1914) also known as ``John of the Mountains '', was a Scottish - American naturalist, author, environmental philosopher, glaciologist and early advocate for the preservation of wilderness in the United States. His letters, essays, and books describing his adventures in nature, especially in the Sierra Nevada, have been read by millions. His activism has helped to preserve the Yosemite Valley, Sequoia National Park and many other wilderness areas. The Sierra Club, which he founded, is a prominent American conservation organization. The 211 - mile (340 km) John Muir Trail, a hiking trail in the Sierra Nevada, was named in his honor. Other such places include Muir Woods National Monument, Muir Beach, John Muir College, Mount Muir, Camp Muir, Muir Grove, and Muir Glacier. In Scotland, the John Muir Way, a 130 - mile - long route, was named in honor of him.
Document 12: Houston: The Baylor College of Medicine has annually been considered within the top ten medical schools in the nation; likewise, the MD Anderson Cancer Center has consistently ranked as one of the top two U.S. hospitals specializing in cancer care by U.S. News & World Report since 1990. The Menninger Clinic, a renowned psychiatric treatment center, is affiliated with Baylor College of Medicine and The Methodist Hospital System. With hospital locations nationwide and headquarters in Houston, the Triumph Healthcare hospital system is the third largest long term acute care provider nationally.
Document 13: Robin Sharman: Robin Sharman (born 8 December 1979) is an English road racing cyclist and coach from Repton, Derbyshire. He competed in the Under-23 road races at the UCI Road World Championships in 2000 and 2001.He represented England at the 2006 Commonwealth Games, competing in the road event but did not finish the race. In February 2009 Sharman was appointed Olympic Development Programme Coach for the Great Britain junior squad, following a year as a coach for British Cycling's Go Ride scheme in the East Midlands.
Document 14: Four Corners, Contra Costa County, California: Four Corners is an unincorporated community in Contra Costa County, California, United States. It is located north-northeast of Walnut Creek, at an elevation of 49 feet (15 m).
Document 15: Four-minute mile: New Zealand's John Walker, the first man to run the mile under 3: 50, managed to run 135 sub-four - minute miles during his career (during which he was the first person to run over 100 sub-four - minute miles), and American Steve Scott has run the most sub-four - minute miles, with 136. Algeria's Noureddine Morceli was the first under 3: 45. Currently, the mile record is held by Morocco's Hicham El Guerrouj, who ran a time of 3: 43.13 in Rome in 1999.
ground_truth: Contra Costa County
sub_queries: What city is Ian Sharman associated with? Answer: Walnut Creek
Walnut Creek >> located in the administrative territorial entity Answer: Contra Costa County