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?
Sentence (from "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.
Relevant evidence: No