I've been reading this great blog and tried to solve B. Troynacci Query but I couldn't :( . I already tried reading its editorial but it contained the equations directly for coding ! I couldn't understand how the equations were derived , and please :

A- I need help to solve the above problem .

B- Can I do all operations and apply modulo at the end when printing only , like :

print : OUTPUT%mod ?

C- I need problems like this to solve .