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>

int main() {

	int n, black = 0, white = 0;
	char stones[200001];

	scanf("%d", &n);
	scanf("%s",  stones);

	for (int i = 0; stones[i] != '\0'; i++) {
		if (stones[i] == '.')
			white++;
		//else if (stones[i] == '#')
		else
			black++;
	}

	if (white > black)
		printf("%d", n - white);
	else if (white < black)
		printf("%d", n - black);

	return 0;
}