Imagine a path that has been paved with shades of light and dark

tiles. Each tile's color can be either a dark shade or a light

shade. You need to find out the minimum number of light tiles to

be replaced by dark tiles so that there exists $k$ consecutive dark

tiles in the path.

Input :

The first line of input consists of a single integer $n$ denoting

the number of tiles in the path.

Second line consists of space separated $n$ integers. The integers

will be either $1$ or $0\mathrm{.}1$ means light tiles. $0$ means dark tiles.

Third line of input consists of a single integer $k$ denoting the

number consecutive dark tiles there has to be in the path

Output:

Output consists of a single integer denoting the minimum number

of light tiles that needs to be replaced with black tiles. If the

path already contains $k$ consecutive dark tiles then the answer is

$0.$