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>

char stones[20000];
int count;

int main(int argc, char const *argv[])
{
    int black = 0, white = 0, max = 0;
    scanf("%d", count);
    scanf("%s", stones);

    for (int i = 0; i < count; i++)
    {
        if (stones[i] == '#')
        {
            black++;
        }
    }

    for (int i = 0; i < count; i++)
    {
        if (stones[i] == '.')
        {
            white++;
        }
        else
        {
            black--;
            if (max < white + black)
                max = white + black;
        }
    }

    printf("%d\n", max);

    return 0;
}