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 Java7 (OpenJDK 1.7.0) (judge verdict: Runtime Error)

import java.util.Scanner;

class Main {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int a;
    String s;
    a = scanner.nextInt();
    s = scanner.next();
    char[] charArray = s.toCharArray();
    int cnt1 = 0;
    int cnt2 = 0;
    if(charArray[0] == '.')
     for(int i=0;i<a||charArray[i]=='.';i++)
     	cnt2--;
    for(int i=0;i<a;i++){
    	if(charArray[i] != '#')
    		cnt1++;
    	else
    		cnt2++;
    }
    if(cnt1 > cnt2)
      System.out.println(cnt2);
    else
      System.out.println(cnt1);
  }
}