In mathematics, the factorial of a positive integer number n is written as n! and is defined as follows: ∏n i=1 are: n! = 1 × 2 × 3 × 4 × . . . × (n − 1) × n = The value of 0! is considered as 1. n! grows very rapidly with the increase of n. Some values of n! 0! = 1 1! = 1 2! = 2 3! = 6 4! = 24 5! = 120 10! = 3628800 14! = 87178291200 18! = 6402373705728000 22! = 1124000727777607680000 You can see that for some values of n, n! has odd number of trailing zeroes (eg 5!, 18!) and for some values of n, n! has even number of trailing zeroes (eg 0!, 10!, 22!). Given the value of n, your job is to find how many of the values 0!, 1!, 2!, 3!, . . . , (n − 1)!, n! has even number of trailing zeroes. Input Input file contains at most 1000 lines of input. Each line contains an integer n (0 ≤ n ≤ 1018). Input is terminated by a line containing a ‘-1’. Output For each line of input produce one line of output. This line contains an integer which denotes how many of the numbers 0!, 1!, 2!, 3!, . . . , n!, contains even number of trailing zeroes. Sample Input 2 3 10 100 1000 2000 3000 10000 100000 i
2/2 200000 -1 Sample Output 3 4 6 61 525 1050 1551 5050 50250 100126