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 C (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>

#define BLACK   '#'
#define WHITE   '.'

int main(void){

  int   n, count;
  char  *s;

  scanf("%d", &n);
  s = malloc(n * sizeof(s));
  scanf("%s", s);

  count = 0;
  for (size_t i = 0; i < n; i++) {
    if (( s[i] == BLACK) && ( s[i + 1] == WHITE)) {
      if (s[i + 2] == BLACK) {
        count++;
      }else if (s[i + 2] == WHITE) {
        count += 2;
      }else{
        count++;
      }
    }
  }

  printf("%d\n", count);

  return 0;

}