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.util.Scanner;

public class Main {

	public static void main(String[] args) {
		
		Scanner scanner = new Scanner(System.in);
		int N = Integer.valueOf(scanner.nextLine());
		String S = scanner.nextLine();
		scanner.close();
		
		char[] c = S.toCharArray();
		int initialBlackPoint = 200000;
		int endBlackPoint = 0;
		int whiteContiCounter = 0;
		boolean existBlack = false;
		
		for (int i = 0; i < N; i++) {
			if (c[i] == '#') {
				if (!existBlack) {
					existBlack = true;
					initialBlackPoint = i;
				} else if (c[i] == '#') {
					endBlackPoint = i;
					whiteContiCounter = 0;
				} else if (c[i] == '.') {
					whiteContiCounter++;
				}
			}
		}
		int counter = 0;
		if (!existBlack) {
			System.out.println(counter);
			return;
		}
		if (whiteContiCounter <=(endBlackPoint - initialBlackPoint + 1)) {
			for (int j = 0; j < N; j++) {
				if (initialBlackPoint <= j && c[j] == '.') {
					counter++;
				}
			}
			System.out.println(counter);
		} else {
			for (int j = 0; j < N; j++) {
				if (j <= initialBlackPoint && endBlackPoint <= j && c[j] == '#') {
					counter++;
				}
			}
			System.out.println(counter);
			
		}
		

	}

}