In Jonah chapter 3 verse 3 and 4, it says: "So Jonah arose and went to Nineveh, according to the word of the Lord. Now Nineveh was an exceedingly great city, a three-day journey in extent. And Jonah began to enter the city on the first day’s walk. Then he cried out and said, 'Yet forty days, and Nineveh shall be overthrown!' "
How is it a three-day journey and he entered the city on the first day's walk?