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 (Clang 3.8.0) (judge verdict: Wrong Answer)

// C.

#include <iostream>
#include <sstream>
#include <algorithm>
#include <vector>

using namespace std;

int main(int argc, char *argv[]) {
	int n;
	cin >> n;
	string s;
	cin >> s;
	int dp[2] = {};
	for (char c : s) {
		int a = dp[0], b = dp[1];
		if (c == '.') {
			dp[0] = a;
			dp[1] = b + 1;
		} else {
			dp[0] = a + 1;
			dp[1] = min(a, b);
		}
	}
	int ans = min(dp[0], dp[1]);

	cout << ans << endl;
	cout << ans << endl;
	return 0;
}