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(void)
{
	char s[200001];
	int a;
	int i;

	scanf("%d", &a);
	scanf("%s", &s);

	int count[2] ;
	for (i = 0; i < 2; i++) {
		count[i] = 0;
	}

	for (i = 0; s[i+1] != '\0'; i++) {
		if (s[i] == '#') {
			if (s[i + 1] == '.') {
				s[i+1] = '#';
				count[0]++;
			}
		}
	}
	for (i = 0; s[i + 1] != '\0'; i++) {
		if (s[i] == '#') {
			if (s[i + 1] == '.') {
				s[i ] = ',';
				count[1]++;
			}
		}
	}

	printf("%d", count[0]);
	int max = 0;
	if (count[0] > count[1]) {
		max = count[1];
	}
	else if(count[0]<count[1]) {
		max = count[0];
	}
	else {
		max = count[0];
	}
	printf("%d\n", max);
	return 0;
}