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>


int main(void){
    int n;
    int i;
    int ca = 0;
    int cb = 0;
    char order[200100];
    
    fgets(order, 200100, stdin);
    sscanf(order, "%d", &n);
    fgets(order, 200100, stdin);
    
    for(i = 0; i < n; i++){
        if(order[0] == '.' && i == 0){
            while(1){
                if(order[i] == '#' || i == n){
                    break;
                }
                i++;
            }
        }
        if(i == n){
            break;
        }
        if(order[i] == '#'){
            ca += 1;
        }
        if(order[i] == '.'){
            cb += 1;
        }
    }
    i -= 1;
    //printf("%d\n", i);
    //printf("%d %d\n", ca, cb);
    if(order[i] == '#'){
        while(1){
            if(i < 0 || order[i] == '.'){
                break;
            }
            ca -= 1;
            i--;
        }
    }
    if(ca == 0 && cb == 0){
        printf("%d\n", 0);
    }else if(ca > cb){
        printf("%d\n", cb);
    }else if(ca < cb){
        printf("%d\n", ca);
    }else{
        printf("%d\n", ca);
    }
    return 0;
}