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(void)
{
	char st[100000];
	int i, n, cnt[100000];
	scanf("%d%*c%s%*c", &n, st);

	int s = 0;
	for(i=0;i<n;i++) {
		if(st[i] == '#') s++;
		cnt[i] = s;
	}
	s = 0;
	for(i=n-1;i>=0;i--) {
		if(st[i] == '.') s++;
		cnt[i] += s;
	}

	int min = 100000;
	for(i=0;i<n;i++) {
		if(min > cnt[i]) min = cnt[i];
	}
	printf("%d", min-1);
	
	return 0;
}