Factstone Benchmark

Amtel has announced that it will release a 128-bit computer chip by 2010, a 256-bit computer by 2020, and so on, continuing its strategy of doubling the word-size every ten years. (Amtel re- leased a 64-bit computer in 2000, a 32-bit computer in 1990, a 16-bit computer in 1980, an 8-bit computer in 1970, and a 4-bit computer, its first, in 1960.) Amtel will use a new benchmark – the Factstone – to advertise the vastly improved capacity of its new chips. The Factstone rating is defined to be the largest integer n such that n! can be represented as an unsigned integer in a computer word. Given a year 1960 ≤ y ≤ 2160, what will be the Factstone rating of Amtel’s most recently released chip? Input There are several test cases. For each test case, there is one line of input containing y. A line containing ‘0’ follows the last test case. Output For each test case, output a line giving the Factstone rating. Sample Input 1960 1981 0 Sample Output 3 8