I don’t know why codechef is not accepting my program .My program is working fine for all test cases and i have seen the other solutions too , they are exactly same as my program.
It is Primality Test problem.

Your code fails when input is 1.
Your output: Yes
Expected Output: No

Handle that and you are good to go !

Still not working

Ok thnaks buddy It is accepted.

Yeah, You missed on to if…else.