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: Time Limit Exceeded)


#include <stdio.h>

int main(void){
    int n, i, j;
    int a = 0;
    int b = 0;
    int c = 30;
    scanf("%d", &n);
    char s[n];
    scanf("%s", s);
    for(i=0;i<=n;i++){
        a=0,b=0;
        for(j=i;j<n;j++){
            if('.' == s[j]){
                a++;
            }
        }
        for(j=i-1; j>=0; j--){
            if('#' == s[j]){
                b++;
            }
        }
        if(a+b < c){
            c = a + b;
        }
    }
    printf("%d", c);
    
    return 0;
}