Score : 300 points
There are N+1 towns. The i-th town is being attacked by A_i monsters.
We have N heroes. The i-th hero can defeat monsters attacking the i-th or (i+1)-th town, for a total of at most B_i monsters.
What is the maximum total number of monsters the heroes can cooperate to defeat?
Input is given from Standard Input in the following format:
N A_1 A_2 ... A_{N+1} B_1 B_2 ... B_N
Print the maximum total number of monsters the heroes can defeat.
2 3 5 2 4 5
9
If the heroes choose the monsters to defeat as follows, they can defeat nine monsters in total, which is the maximum result.
3 5 6 3 8 5 100 8
22
2 100 1 1 1 100
3