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++14 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <bits/stdc++.h>

using namespace std;

int main(){

    int N;
    string S;

    cin >> N;
    cin >> S;

    int ans = 20000000;
    for(int i = 0; i < N+1; i++){
	string cand('#', N);
	for(int j = 0; j < N; j++){
	    cand.at(j) = '#';
	}
	for(int j = 0; j < i; j++){
	    cand.at(j) = '.';
	}
	//cout << cand << endl;
	int sum = 0;
	for(int j = 0; j < N; j++){
	    if(S.at(j) != cand.at(j)){
		sum++;
	    }
	}
	//cout << sum << endl;
	ans = min(ans, sum);
    }

    cout << ans << endl;
    
}