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 sc = new Scanner(System.in);

		int n=Integer.parseInt(sc.next());

		String str=sc.next();
		String sh="#";
		String dottt=".";
		int cnt,cnt2;

		String[] str2=str.split(""); //一文字ずつ取り出す
		String[] str3=str.split("");
		cnt=0;
		cnt2=0;

		for(int i=0;i<n-1;i++){
			if(str2[i].equals(sh)==true&&str2[i+1].equals(dottt)==true){
				cnt+=1;
				str2[i+1]=dottt;
			}
			if(str3[i].equals(sh)==true&&str3[i+1].equals(dottt)==true){
				cnt2+=1;
				str2[i]=sh;
			}
		}
		if(cnt>cnt2)cnt=cnt2;
		System.out.println(cnt);
		sc.close();

	}

}