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.*;

class Main {
    // 150d
    static final long MOD = 1_000_000_007;
    static final int MAX = 2000000000;
    static final int INF = 100000000;

    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        char[] str = sc.next().toCharArray();
        sc.close();
        char index = str[0];
        //int[] num = new int[n];
        //int m = 0;
        int ans = 0;
        int fwhite = 0;
        boolean brack = true;
        for(int i = 0;i < n;i++){
            if(str[i] == '.')ans++;
            if(brack&&str[i]!=index){
                brack = false;
            }
            if(brack&&str[i] == '.')fwhite++;
        }
        System.out.println(ans-fwhite);
    }
}