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 (gfortran v4.8.4) (judge verdict: Accepted)

integer(16) N
character(2*10**5) S
integer(16) kcnt,scnt,i
integer ans
read*,N,S
kcnt=0
scnt=0
do i=1,N
  if(S(i:i)==".")scnt=scnt+1
end do
ans=min(scnt,N-scnt)
do i=1,N
  if(S(i:i)=="#")kcnt=kcnt+1
  if(S(i:i)==".")scnt=scnt-1
  if(S(i:i)/=S(i+1:i+1))then
    ans=min(ans,scnt+kcnt)
  endif
end do
print"(I0)",ans
end