Number of trailing zeroes of a given number

My code is working fine one ideone but fails to submit on codechef.

I am new to programming. I was in the practice section of codechef. The problem is quite simple that is to find the total number of trailing zeros in factorial of a given number. My code works fine with the test case provided by them in input section but when I try to submit the code it says "“Wrong Answer” here is my codechef submitted file link.

I know that there are already many submissions for this question on codechef but I want to know exactly what is wrong in my code.

The condition within your while loop is a bit wrong.
For n=25, your code gives 5 as the answer. But 25! is 15511210043330985984000000 (6 trailing zeroes).

I was missing an equal to sign.