Question: In what county is the city containing KSTZ located?

full_context: Document 1: KRST: KRST (Nash FM 92.3 KRST) is a commercial radio station located in Albuquerque, New Mexico, broadcasting to the Albuquerque-Santa Fe, New Mexico area on 92.3 FM. KRST airs a country music format owned by Cumulus Media. Its studios are located in Downtown Albuquerque and the transmitter tower is located atop Sandia Crest east of the city.
Document 2: Colo, Iowa: Colo is a city in Story County, Iowa, United States. The population was 876 at the 2010 census. It is part of the Ames, Iowa Metropolitan Statistical Area, which is a part of the larger Ames-Boone, Iowa Combined Statistical Area.
Document 3: KPSZ: KPSZ (940 AM, "Praise 940") is a Christian radio station serving the Des Moines, Iowa, area. The station's studios are located on Locust Street in Des Moines along with Saga Communications' other Des Moines stations (KRNT, KSTZ, KIOA, KMYR and KAZR), while its 8-tower transmitter array is located near Hartford.
Document 4: Adult contemporary music: Other popular names for the format include "Warm", "Sunny", "Bee" (or "B") and (particularly in Canada) "EZ Rock". The format can be seen as a more contemporary successor to and combination of the middle of the road (MOR), beautiful music, easy listening and soft rock formats. Many stations in the soft AC format capitalize on its appeal to office workers (many of them females aged 25–54, a key advertiser demographic), and brand themselves as stations "everyone at work can agree on" (KOST originated that phrase as a primary tagline, and other soft AC stations have followed suit).
Document 5: KESZ: KESZ (99.9 FM; "KEZ") is an adult contemporary radio station based in Phoenix, Arizona. The station is owned and operated by iHeartMedia. Its studios are located in Phoenix near Sky Harbor Airport and its transmitter is in South Mountain Park.
Document 6: Indianola, Iowa: Indianola is a city in Warren County, Iowa, United States, 18 miles south of Des Moines, Iowa. The population was 14,782 at the 2010 census. It is the county seat of Warren County.
Document 7: Kalona, Iowa: Kalona is a city in Washington County, Iowa, United States. It is part of the Iowa City, Iowa Metropolitan Statistical Area. The population was 2,363 at the 2010 census. Kalona is the second largest city in Washington County.
Document 8: Des Moines metropolitan area: The Des Moines metropolitan area, officially known as the Des Moines -- West Des Moines, IA Metropolitan Statistical Area (MSA), consists of five counties in central Iowa, United States: Polk, Dallas, Warren, Madison, and Guthrie. The 2010 census population of these counties was 569,633, and the 2017 estimated population was 645,911.
Document 9: KRBZ: KRBZ, 96.5 FM in Kansas City, is an alternative rock station. The station uses the brand name 96-5 The Buzz. The station is owned by Entercom Communications, with studios located in Mission, Kansas and a transmitter site in Kansas City's East Side.
Document 10: Fort Dodge, Iowa: Fort Dodge is a city in and the county seat of Webster County, Iowa, United States, along the Des Moines River. The population was 25,206 in the 2010 census, an increase from 25,136 in the 2000 census. Fort Dodge is a major commercial center for North Central and Northwest Iowa. It is located on U.S. Routes 20 and 169.
Document 11: Saylorville, Iowa: Saylorville is a census-designated place (CDP) in Polk County, Iowa, United States. The population was 3,301 at the 2010 census. It is part of the Des Moines–West Des Moines Metropolitan Statistical Area. The Saydel Community School District is located in this area. The unincorporated community of Marquisville is in this area.
Document 12: KSTZ: KSTZ (102.5 FM, "Star 102.5") is a commercial FM radio station in Des Moines, Iowa. The station has a Hot Adult Contemporary radio format. KSTZ is part of Saga Communications' Des Moines Radio Group, along with KPSZ, KRNT, KAZR, KIOA, and KMYR, with studios located on Locust Street in Des Moines.
Document 13: Middletown, Iowa: Middletown is a city in Des Moines County, Iowa, United States. The population was 318 at the 2010 census. It is part of the Burlington, IA–IL Micropolitan Statistical Area.
Document 14: WZST: WZST is an adult hits formatted broadcast radio station licensed to Westover, West Virginia, serving the Morgantown/Fairmont area. WZST is owned and operated by Laurel Highland Total Communications, Inc., through licensee LHTC Media of West Virginia, Inc.
Document 15: Corydon, Iowa: Corydon is a city in Wayne County, Iowa, United States. The population was 1,585 in the 2010 census, a decline from 1,591 in the 2000 census. It is the county seat of Wayne County.
ground_truth: Warren County
sub_queries: What city is KSTZ located? Answer: Des Moines
Des Moines >> located in the administrative territorial entity Answer: Warren County