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.*;
import java.io.*;
import java.nio.charset.StandardCharsets;

public class Main {
	int N;
	String S;
	int result = 0;
	
	Main() throws IOException{
		InputStreamReader reader = new InputStreamReader(System.in, StandardCharsets.UTF_8);
		BufferedReader in = new BufferedReader(reader);
		N = Integer.parseInt(in.readLine());
		S = in.readLine();
		in.close();
		calc();
	}
	
	void calc() {
		boolean replaceMode = false;
		for(int i= 0; i < S.length(); ++i) {
			if(!replaceMode) {
				if(S.charAt(i) =='#') {
					replaceMode = true;
				}
			}else {
				if(S.charAt(i) == '.') {
					++result;
				}
			}
		}
	}

	public static void main(String[] args) throws IOException {
		Main ins = new Main();
		System.out.println(ins.result);
		

	}

}