I am solving a problem on codechef answer on my machine are correct but i m getting WA error on codechef

Question

I am solving a problem on codechef answer on my machine are correct but i m getting WA error on codechef.

I think i have checked for constraint,but i m getting WA(wrong answer error)

this is the problem
https://www.codechef.com/problems/CHEFROUT

this is my code
https://www.codechef.com/viewsolution/16738420

it would be very helpful for me if you check my solution and tell me the reason of error(or atleast that my solution is not wrong,but also preferably why i m getting error) .I will be very thankful.