Question: What is the population of the largest city in Iraq, who's 1956–57 Iraq FA Cup Championship was open to teams from the capital?

Context paragraphs:
1984–85 Iraq FA Cup: The 1984–85 Iraq FA Cup was the ninth edition of the Iraq FA Cup.  The tournament was abandoned at the semi-final stage with Al-Rasheed, Al-Tayaran, Al-Talaba and Al-Tijara being the four teams still remaining in the competition.  It was abandoned along with the 1984–85 Iraqi National League due to the national team's World Cup qualifying campaign, and no champions were announced for either tournament.

2016 Iraq FA Cup Final: The 2016 Iraq FA Cup Final was the 32nd final of the Iraq FA Cup.  The match was contested between the Baghdad rivals, Al-Zawra'a and Al-Quwa Al-Jawiya, at Al-Shaab Stadium in Baghdad.  It was played on 29 May 2016 to be the final match of the competition.  Al-Quwa Al-Jawiya made their 7th appearance in the Iraq FA Cup final while Al-Zawra'a extended their record to 16 final appearances.  Al-Quwa Al-Jawiya won the match 2–0 with goals from Bashar Rasan and Humam Tariq, for the club's 4th title.

1956–57 Iraq FA Cup Championship: The 1956–57 Iraq FA Cup Championship was the 2nd season of what is now known as the League of the Institutes (the top division of Iraqi football from 1948 to 1974), and it was the first national championship to be held since the 1948–49 season.  Unlike that season, this time it was open to teams from Baghdad only.

2016–17 Iraq FA Cup: The 2016–17 Iraq FA Cup was the 28th edition of the Iraqi knockout football cup competition, the main domestic cup in Iraqi football.  A total of 19 teams from the Iraqi Premier League and 41 teams from the Iraq Division One participated.  It started on 2 December 2016 and the final was played at the Al-Sinaa Stadium in Baghdad on 22 August 2017 (the usual venue, Al-Shaab Stadium, was closed for renovation).  It was the second Iraq FA Cup final to be held outside of Al-Shaab Stadium, with the first being in 2003.

1989–90 Iraq FA Cup: The 1989–90 Iraq FA Cup was the 13th edition of the Iraq FA Cup.  The tournament was won by Al-Zawraa for the sixth time, beating Al-Shabab 2–1 on penalties in the final after a 0–0 draw.  The first three rounds were between teams from the lower division, before the top-flight clubs began to enter at the round of 32.

Baghdad: Baghdad (Arabic: بغداد‎ ‎ , ) is the capital of Iraq.  The population of Baghdad, as of 2016 , is approximately 8,765,000, making it the largest city in Iraq, the second largest city in the Arab world (after Cairo, Egypt), and the second largest city in Western Asia (after Tehran, Iran).

1979–80 Iraq FA Cup: The 1979–80 Iraq FA Cup was the fourth edition of the Iraq FA Cup.  The tournament was won by Al-Jaish for the first time, beating Al-Talaba 4–2 on penalties in the final after a 1–1 draw in which Jamal Ali scored Al-Talaba's goal.  The first two rounds were between teams from the lower division, before the top-flight clubs entered at the round of 16.

1987–88 Iraq FA Cup: The 1987–88 Iraq FA Cup was the 11th edition of the Iraq FA Cup.  The tournament was won by Al-Rasheed for the second consecutive time, beating Al-Zawraa 4–3 on penalties in the final after a 0–0 draw.  Al-Rasheed won the 1987–88 Iraqi National League as well to complete their second double in a row.  It was also Al-Zawraa's first FA Cup final defeat.

Iraqi Super Cup: The Iraqi Super Cup (Arabic: كأس السوبر العراقي), previously called Al-Muthabara Cup (Arabic: كأس المثابرة, meaning "Perseverance Cup"), is Iraqi football's annual match contested between the champions of the previous Iraqi Premier League season and the holders of the Iraq FA Cup at Al-Shaab Stadium.  If the Premier League champions also won the FA Cup then the league runners-up provide the opposition.  Generally ranked below the Iraq FA Cup and the now-defunct Iraqi Elite Cup in terms of importance, the fixture is a recognised football super cup.

1988–89 Iraq FA Cup: The 1988–89 Iraq FA Cup was the 12th edition of the Iraq FA Cup.  The tournament was won by Al-Zawraa for the fifth time, beating Al-Tayaran 3–0 in the final.  The first two rounds were between teams from the lower division, before the top-flight clubs entered at the round of 32.

Supporting paragraphs: 1956–57 Iraq FA Cup Championship Baghdad
Answer: 8,765,000