Hello Hello : CodeChef Problem HELLO

Problem Statement:
Chef talks a lot on his mobile phone. As a result he exhausts his talk-value (in Rokdas) very quickly. One day at a mobile recharge shop, he noticed that his service provider gives add-on plans which can lower his calling rates (Rokdas/minute). One of the plans said “Recharge for 28 Rokdas and enjoy call rates of 0.50 Rokdas/min for one month”. Chef was very pleased. His normal calling rate is 1 Rokda/min. And he talked for 200 minutes in last month, which costed him 200 Rokdas. If he had this plan activated, it would have costed him: 28 + 0.5*200 = 128 Rokdas only! Chef could have saved 72 Rokdas. But if he pays for this add-on and talks for very little in the coming month, he may end up saving nothing or even wasting money. Now, Chef is a simple guy and he doesn’t worry much about future. He decides to choose the plan based upon his last monthâ€™s usage.

There are numerous plans. Some for 1 month, some for 15 months. Some reduce call rate to 0.75 Rokdas/min, some reduce it to 0.60 Rokdas/min. And of course each of them differ in their activation costs. Note – If a plan is valid for M months, then we must pay for (re)activation after every M months (once in M months). Naturally, Chef is confused, and you (as always) are given the task to help him choose the best plan.