def collatz_to_one(n):
    chainLength = 1
    while (n > 1):
        if n % 2 == 0:
            n = n/2
        else:
            n = 3 * n + 1
        chainLength += 1
    return chainLength

longestChain = 0

for i in range(1000000):
    currentChain = collatz_to_one(i)
    if currentChain > longestChain:
        longestChain = currentChain
        print("current longest chain: " + str(longestChain) + " (from " + str(i) + ")")

print("done")