You are playing a game that consists of $n$ levels. Each level has a monster. On levels $1,2,\dots,n-1$ , you can either kill or escape the monster. However, on level $n$ you must kill the final monster to win the game.
Killing a monster takes $sf$ time where $s$ is the monster's strength and $f$ is your skill factor. After killing a monster, you get a new skill factor (lower skill factor is better). What is the minimum total time in which you can win the game?
The first input line has two integers $n$ and $x$ : the number of levels and your initial skill factor.
The second line has $n$ integers $s_1,s_2,\dots,s_n$ : each monster's strength.
The third line has $n$ integers $f_1,f_2,\dots,f_n$ : your new skill factor after killing a monster.
Print one integer: the minimum total time to win the game.
5 100 50 20 30 90 30 60 20 20 10 90· \n · · · · \n · · · · \n
2600\n
The best way to play is to kill the second and fifth monster.