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 Python (3.4.3) (judge verdict: Runtime Error)

N = int(input())
S = list(input())

count_list =[]
wc = 0

A=[0]*(N+1)

for i in list(range(N))[::-1]:
    if(S[i] == '#'):
        A[i] = A[i+1] + 1

print(A)
for n in range(N-1):
    if(S[n] == '.'):
        num = n
        count_list.append(A[n+1] + wc)
        wc += 1

if(S[N-1] == '.'):
    count_list.append(wc+1)

count = min(count_list)
print(count)