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 {
        Scanner sc = new Scanner(System.in);
        int num = Integer.parseInt(sc.next());
        int ans = 0;
        if (num > 0) {
            String str = sc.next();
            String value1 = "#";
            String value2 = ".";
            int value1Count = 0;
            int value2Count = 0;
            boolean whiteFlag = false;
            int whiteCount = 0;
            
            String tmpValue = "";
            for (int i = 0; i < num; i++) {
                tmpValue = String.valueOf(str.charAt(i));
                if (tmpValue.equals(value1)) {
                    whiteFlag = true;
                    value1Count++;
                } else if (tmpValue.equals(value2)) {
                    if (whiteFlag) {
                        value2Count++;
                    } else {
                        whiteCount++;
                    }
                } else {
                    
                }
            }
            
            if (value1Count >= value2Count) {
                if (value1Count >= value2Count + whiteCount) {
                    ans = value1Count;
                } else {
                    ans = value2Count;
                }
            } else if (value1Count <= value2Count) {
                ans = value1Count;
            } else {
                ans = 0;
            }
        }
        System.out.println(ans);
    }
}