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>
#define N 2*10*10*10*10*10

int main(void){
    int n,i,j,count=0;//nは石の個数、iはループ用、カウントは変えるべき石の個数
    char s[N];

    scanf("%d",&n);
    scanf("%s",s);

for(j=0;j<2;j++){
    for(i=0;i<n;i++){
        if(s[i]=='.'){
            if(s[i-1]=='#'){
                count++;
                s[i]='#';
            }
        }
    }
    for(i=0;i<n;i++){
        if(s[i]=='#'){
            if(s[i+1]=='.'){
                count++;
                s[i]='.';
            }
        }
    }
}

printf("%d",count);
return 0;
}