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.*;
 
public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int N = sc.nextInt();
        String line = sc.next();
        String S[] = line.split("");
        boolean wasSharp = false;
        boolean wasDot = false;
        int count1 = 0;
        int count2 = 0;
        int total = 0;
        for(int i = 0; i < N ;i++){
            if(S[i].equals("#")){
                wasSharp = true;
                count1++;
                continue;
            }
            if(wasSharp&&S[i].equals(".")){
                for(int j = i; j < N; j++){
                    if(!S[j].equals("#")){
                        count2++;
                    }else{
                        i = j;
                        break;
                    }
                }
                wasSharp = false;
                if(count1 > count2){
                    total += count2;
                }else{
                    total += count1;
                }
                count1 = 0;
                count2 = 0;
            }
        }
        System.out.println(total);
    }
}