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) {
		// TODO 自動生成されたメソッド・スタブ
		Scanner sc = new Scanner(System.in);
		int N = sc.nextInt();
		String S = sc.next();
		int count = 0;
		String[] array = S.split("");

		if (array.length == 1) {
			System.out.println(0);
			System.exit(0);
		}

		for (int i = 0; i < array.length - 1; i++) {
			if (array[i].equals("#")) {
				if (array[i + 1].equals(".")) {
					array[i + 1] = "#";
					count++;
				}
			}

			if (array[i].equals(".")) {
				if (array[i + 1].equals("#")) {
					array[i] = "#";
					count++;
				}

			}

		}

		System.out.println(count);
	}

}