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 Fortran (GNU Fortran 9.2.1) (judge verdict: Runtime Error)

program prob3
    implicit none
    integer::N,i,j,l,w,b
    character(len=200005)::S
    read(*,*) N, S
    l = len_trim(S)
    w = 0
    b = 0
    do i = 1, l
        if(S(i:i) .eq. ".") then
            j = i
        end if
    end do
    do i = 1, j
        if(S(i:i) .eq. ".") then
            w = w + 1
        else
            b = b + 1
        end if
    end do
    write(*,*) min(w,b)
    stop
end program