CF215D Hot Days

The official capital and the cultural capital of Berland are connected by a single road running through $ n $ regions. Each region has a unique climate, so the $ i $ -th $ (1

The first input line contains two integers $ n $ and $ m $ $ (1

Print the only integer — the minimum number of roubles the organizers will have to spend to transport all schoolchildren. Please, do not use the %lld specifier to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d specifier.

In the first sample the organizers will use only one bus to travel through the first region. However, the temperature in the bus will equal $ 30+10=40 $ degrees and each of $ 10 $ schoolchildren will ask for compensation. Only one bus will transport the group through the second region too, but the temperature inside won't exceed the limit. Overall, the organizers will spend $ 100+10+10=120 $ rubles.