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 Ruby (2.3.3) (judge verdict: Wrong Answer)


n = gets.chomp.to_i

s = gets.chomp

boundaries = []
curr = ""

min = 9999999999

s.chars.each_with_index do |a,i|

  if(a != curr)
    
    boundaries.push(i) if a == "#"
    curr = a
  
  end

end


if (boundaries.length == 0 || boundaries.length == 1)
  min = 0
end


boundaries.each do |j|

  front = s.slice(0, j)
  back = s.slice(j, s.length)
  
  p1 = front.count("#")
  p2 = back.count(".")
  sum = p1 + p2

  min = sum if(min > sum)

end

puts min