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.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {
	public static void main(String[] args) throws Exception {
		
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		String line = reader.readLine();
		int N = Integer.parseInt(line);
		String[] str = reader.readLine().split("");
		int ans = N;
		int white = 0;
		int black = 0;
		int[] ans_j = new int[N];
		for (int j = 0; j < N; j++) {
		    for (int i = 0; i < N; i++) {
				if (i <= j && str[i].equals("#")) {
					black++;
				}
				else if (i > j && str[i].equals(".")) {
					white++;
				}
			}
			ans_j[j] = black + white;
			white = 0;
		    black = 0;
		}
		for (int i = 0; i < N; i++) {
			if (ans_j[i] < ans) {
				ans = ans_j[i];
			}
		}
		System.out.println(ans);
	}
}