Please help me in problem NUKES

I am facing problem with this question:https://www.codechef.com/problems/NUKES

My solution is:https://www.codechef.com/viewsolution/17193614

I am getting time limit exceeded, only in case 5, 6 ,7. All other cases are being excepted. I tried optimizing the code by adding a while loop, but yet no effect. Please help.