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 size = scanner.nextInt();
        String str = scanner.next();
        
        boolean lastFlag = str.charAt(size-1) == '#' ? true : false;
        int breakInt = -1;
        if(lastFlag) {
            int index = 0;
            for(int i = size-1; i >=0; i--) {
                if(str.charAt(i) == '.') {
                    breakInt = size - index;
                    break;
                }
                index++;
            }
        }

        int count1 = 0;
        int count2 = 0;
        boolean flag = false;
        for(int i = 0; i < size; i++) {
            if(!flag && str.charAt(i) == '#') flag = true;
            if(flag) {
                if(i == breakInt) break;
                if(str.charAt(i) == '.') count1++;
                if(str.charAt(i) == '#') count2++;
            }
        }

        int count = count1 > count2 ? count2 : count1;

        System.out.println(count);
    }
}