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: Wrong Answer)

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;


int main(){
	
	int N;
	int a = 0;
	int b = 0;
	string S;
	cin >> N >> S;
	int n = N - 1;

	for (int i = 0; i < N; i++) {
		if (S[n - i] == '.') {
			for (int j = 0; j <= n - i; j++) {
				if (S[j] == '.') a++; 
				else  b++;

			}
			cout << min(a,b) << endl;
			break;
		}
		cout << min(a, b) << endl;
	}

	return 0;
}