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 ()
{
    char *s;
    int n;
    int i;//制御
    int w=0,b=0;
    int kazu=0;//変えなきゃいけない回数
    scanf("%d",&n);
    s=malloc(sizeof(char)*n);
    scanf("%s",s);
    for(i=0;i<n;i++){
        if(s[i]=='.')
        w++;
        else 
        {
            b++;
        }
        
    }
    if(w<=b){
        for(i=0;i<n;i++){
            if(s[i]!='.')
            break;
        }
        for(i=i;i<n;i++){
            if(s[i]=='.')
            kazu++;
        }
    
    }
    else if(w>b){
        //printf("kokonikita");
        for(i=0;i<n;i++){
            if(s[i]=='#')
            kazu++;
        }
    }
    printf("%d\n",kazu);
    return 0;
}