Score : 300 points
There are N candles placed on a number line. The i-th candle from the left is placed on coordinate x_i. Here, x_1 < x_2 < ... < x_N holds.
Initially, no candles are burning. Snuke decides to light K of the N candles.
Now, he is at coordinate 0. He can move left and right along the line with speed 1. He can also light a candle when he is at the same position as the candle, in negligible time.
Find the minimum time required to light K candles.
Input is given from Standard Input in the following format:
N K x_1 x_2 ... x_N
Print the minimum time required to light K candles.
5 3 -30 -10 10 20 50
40
He should move and light candles as follows:
3 2 10 20 30
20
1 1 0
0
8 5 -9 -7 -4 -3 1 2 3 4
10