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 Java8 (OpenJDK 1.8.0) (judge verdict: Wrong Answer)

import java.io.*;
public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader bf = 
            new BufferedReader(new InputStreamReader(System.in));
        int N = Integer.parseInt(bf.readLine());
        String S = bf.readLine();
        int min = N;
        for(int i = 0; i < N; i++){
            for(int j = i, count = 0; j < N; j++, count = 0){
                for(int k = 0; k < j; k++){
                    if(S.charAt(k) == '#'){
                        count++;
                    }
                }
                for(int k = j; k < N; k++){
                    if(S.charAt(k) == '.'){
                        count++;
                    }
                }
                min = Math.min(min, count);
            }
        }
        System.out.println(min);
    }
}