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>

int main(){
	int n, k;
	char *s;
	
	scanf("%d", &n);
	s = malloc(sizeof(char) * (long)n);
	scanf("%s", s);
	int min = n;
	for(int i = n - 1; i >= 0; --i){
		if(s[i] == '#'){
			min = i;
		}
	}
	int ret = 0;
	for(int i = min; i < n; ++i){
		if(s[i] == '.'){
			++ret;
		}
	}
	
	int tmp = 0;
	int max = 0;
	for(int i = 0; i < n; ++i){
		if(s[i] == '.'){
			max = i;
		}
	}
	
	for(int i = 0; i <= max; ++i){
		if(s[i] == '#'){
			++tmp;
		}
	}
	
	printf("%d\n", ret < tmp ? ret : tmp);
	free(s);
	return 0;
}