When looking at all hailstone sequences from 1 to z, maxHail(z) will return the starting number that creates the longest sequence. In other words, maxHail(n) looks at hailLen(1), hailLen(2) ... hailLen(n) and returns the number from 1-n that had the largest hailstone sequence. You should look at the hailLen() problem before working on this. You should use your solution from the hailLen() problem. ( http://codingbat.com/author/p264289 ) since hailLen(3) is larger than the hailLen of 4 or 5, maxHail of 3,4,5 all return 3. Since 6 has a longer sequence, maxHail(6) gives us 6. remember: Use the hailLen function you already wrote!