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) {
		Scanner sc = new Scanner(System.in);
		int n, i;
		int bcount = 0, wcount = 0;
		String s;
		n = sc.nextInt();
		s = sc.next();
		char[] sArray = s.toCharArray();

		for(i = 0; i < n - 1; i++) {
			if(sArray[i] == '#') {
				if(sArray[i + 1] == '.') {
				    bcount++;
				    sArray[i + 1] = '#';
				}
			}else if(sArray[i] == '.') {
				if(sArray[i + 1] == '#') {
				    wcount++;
				    sArray[i + 1] = '.';
				}
			}
		}
		if(wcount > bcount){
		    System.out.println(wcount);
		}else{
		    System.out.println(bcount);
		}
		sc.close();
	}
}