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.Scanner;

class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        int N = sc.nextInt();
        char[] S = new char[N];
        S = sc.next().toCharArray();

        int firstEmerge = 0;
        for (int i=0; i<N; i++) {
            if (S[i] == '#') {
                firstEmerge = i;
                break;
            }
        }

        int countSharp = 0;
        int countDot = 0;
        for (int i=firstEmerge; i<N; i++) {
            if (S[i] == '#') {
                countSharp++;
            } else {
                countDot++;
            }
        }
        System.out.println(Math.min(countSharp, countDot));
    }
}