Score : 500 points
For an integer n not less than 0, let us define f(n) as follows:
Given is an integer N. Find the number of trailing zeros in the decimal notation of f(N).
Input is given from Standard Input in the following format:
N
Print the number of trailing zeros in the decimal notation of f(N).
12
1
f(12) = 12 × 10 × 8 × 6 × 4 × 2 = 46080, which has one trailing zero.
5
0
f(5) = 5 × 3 × 1 = 15, which has no trailing zeros.
1000000000000000000
124999999999999995