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 <bits/stdc++.h>
using namespace std;


int main()
{
	int N;
	string S;
	cin >> N >> S;

	int ans = 0;
	int ans2 = 0;

	int i = 0;
	int a = 0;
	while (i < N && S[i] == '.') ++i;
	a = i;
	if (i == N) {
		cout << ans << endl;
		return 0;
	}
	else {
		for (; i < N; ++i) {
			if (S[i] == '.') {
				++ans;
			}
		}
	}

	cout << min(ans, N - a - ans) << endl;
}