12-6084

for n in range(1, 1000):
    s = "2" * n + "1" * n
    N=len(s)
    while "12" in s or "21" in s:
        if "12" in s:
            s = s.replace("12", "21", 1)
        else:
            s = s.replace("21", "111", 1)
    if s.count("1") > 100:
        print(s.count("1"), N)
        break