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 <vector>
#include <algorithm>
#include <string>
#include <fstream>
#include <math.h>
#include <map>
using namespace std;

int main()
{
	int N;
	string S;
	int ANS1=0;
	int ANS2=0;
	cin >> N;
	cin >> S;

	for(int i=0;i<N;i++)
	{
		if(S[i]=='#')
		{
			ANS1++;
		}
	}

	for(int i=0;i<N-1;i++)
	{
		cout << "S[i]:" << S[i] << endl;
		if(S[i]=='#' && S[i+1]=='.')
		{
			ANS2++;
			S[i+1]='#';
		}
	}
	cout << min(ANS1,ANS2) << endl;

}