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++ (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
 
#define FAST ios_base::sync_with_stdio(0); cin.tie(); cout.tie();
 
#define MAXX 100005
 
#define PI 3.14159265358979323846264338327950
 
#define F first
#define S second
 
#define ll 	 long long int
 
#define mod  1000000007

map<string, int> m;




int main()
{
	FAST;
	ll n;
	cin >> n;
	string s;
	cin >> s;
	ll ans = 0;
	for(ll i = 0; i + 1 < s.size() ; i ++){
		if((s[i] == '#' && s[i+1] == '.') || (s[i] == '.' && s[i+1] == '#')){
			if(s[i+1] == '.'){
				s[i+1] = '#';
			}
			if(s[i] == '.'){
				s[i+1] = '#';
			}
			ans ++;
		}
	}
	cout << ans;
	return 0;
}