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: Runtime Error)

#include <stdio.h>

int main() {
  long long int i, number, j, k, count_black = 0, count_white = 0, temp, ans;
  scanf("%lld", &number);
  char stone[number + 1];
  fgets(stone, number + 1, stdin);
  for(i = 0; i < number; i++) {
    if(stone[i] == '#') {
      j = i;
      break;
    }
  }
  for(i = number - 1; j <= i; i--) {
    if(stone[i] == '.') {
      k = i;
      break;
    }
  }
  for(i = j; i <= k; i++) {
    if(stone[i] == '.') {
      count_white++;
    } else {
      count_black++;
    }
  }
  ans = (count_white < count_black)? count_white: count_black;
  printf("%lld\n",ans);
  return 0;
}