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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <stdio.h>

int
main(void)
{
        int N;
        char *S;
        char black = 0;
        int count = 0;

        scanf("%d\n", &N);

        for (int i = 0; i < N; i++) {
                char c;
                char stone;
                int ret = scanf("%c", &c);
                if (ret == EOF)
                        break;

                if (c == '.')
                        stone = 0;
                else if (c == '#')
                        stone = 1;

                if (stone == 1)
                        black = 1;

                if (black == 1 && stone == 0)
                        count++;
        }

        printf("%d", count);

        return 0;
}