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: Runtime Error)

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {


		Scanner sc = new Scanner(System.in);

		//入力
		sc.nextInt();
		sc.nextLine();
		String inputStr = sc.next();


		int cnt1 = 0;
		int cnt2 = 0;
		int cnt3 = 0;
		int cnt4 = 0;



		int k = 0;

		while(inputStr.charAt(k) == '.') {

			k += 1;

		}

		int m = inputStr.length();

		while(inputStr.charAt(m-1) == '#') {

			m -= 1;

		}

		for(int l = k ; l < m ; l++) {

			if(inputStr.charAt(l) == '.') {

				cnt3 += 1;

			}else if(inputStr.charAt(l) == '#') {

				cnt4 += 1;

			}

		}

		int min3 = Math.min(cnt3, cnt4);

		for(int i = 0 ; i < inputStr.length() ; i++) {

			if(inputStr.charAt(i) == '.') {

				cnt1 += 1;

			}else if(inputStr.charAt(i) == '#') {

				cnt2 += 1;

			}

		}

		if(cnt1 < cnt2) {


			if(inputStr.charAt(0) == '.') {
				cnt1 -= 1;
				//System.out.println(cnt1-1);
			}else {
				//System.out.println(cnt1);
			}




		}else if(cnt1 > cnt2) {

			if(inputStr.charAt(inputStr.length()-1) == '#') {
				cnt2 -= 1;
				//System.out.println(cnt2-1);
			}else {
				//System.out.println(cnt2);
			}


		}else if(cnt1 == cnt2) {

			if(inputStr.charAt(inputStr.length()-1) == '#' || inputStr.charAt(0) == '.') {
				//System.out.println(cnt2-1);
				cnt2 -= 1;
			}else {
				//System.out.println(cnt2);
			}

		}


		int min1 = Math.min(cnt1, cnt2);
		int min2 = Math.min(min3, min1);


		System.out.println(min2);
		sc.close();
	}

}