Task: Question Answering
Input (English): Passage: Mehmed built a fleet to besiege the city from the sea .Contemporary estimates of the strength of the Ottoman fleet span between about 110 ships , 145 , 160 , 200-250  to 430 . A more realistic modern estimate predicts a fleet strength of 126 ships comprising 6 large galleys, 10 ordinary galleys, 15 smaller galleys, 75 large rowing boats, and 20 horse-transports.:44 Before the siege of Constantinople, it was known that the Ottomans had the ability to cast medium-sized cannons, but the range of some pieces they were able to field far surpassed the defenders' expectations. Instrumental to this Ottoman advancement in arms production was a somewhat mysterious figure by the name of Orban , a Hungarian .:374 One cannon designed by Orban was named "Basilica" and was 27 feet  long, and able to hurl a 600 lb  stone ball over a mile . 
Question: How many more ordinary galleys than large galleys did the Ottoman fleet possess? 
Answer type: Number 
Output (English): 4.