Problem:
Score : 300 points

Problem Statement

There are N stones arranged in a row. Every stone is painted white or black.
A string S represents the color of the stones. The i-th stone from the left is white if the i-th character of S is ., and the stone is black if the character is #.

Takahashi wants to change the colors of some stones to black or white so that there will be no white stone immediately to the right of a black stone.
Find the minimum number of stones that needs to be recolored.

Constraints

1 \leq N \leq 2\times 10^5

S is a string of length N consisting of . and #.

Input

Input is given from Standard Input in the following format:

N
S

Output

Print the minimum number of stones that needs to be recolored.

Sample Input 1

3
#.#

Sample Output 1

1

It is enough to change the color of the first stone to white.

Sample Input 2

5
#.##.

Sample Output 2

2

Sample Input 3

9
.........

Sample Output 3

0

Solution in Julia (0.5.0) (judge verdict: Runtime Error)

parseInt(x)=parse(Int,x)
parseMap(x::Array{SubString{String},1})=map(parseInt,x)

function main()
	n = readline() |> parseInt
	s = chomp(readline())
	c = 0
	cc = 0
	for i in 0:n-1
		if s[n-i] == '.'
			cc = n-i
			break
		end
	end
	for i in 1:cc
		if s[i] == '.'
			count += 1
		end
	end
	if count == cc
		println(0)
	elseif c <= cc/2
		println(c)
	else
		println(cc-c)
	end
end
main()