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 c;
  cin >> n >> c;
  string s;
  s = c;
  int ct = 0;
  int ct1 =0;
  //.を#に変えるカウント                                                                                                                                                                                    
  for(int i=0;i<n-1;i++){
    if(s[i]=='#'&&s[i+1]=='.'){
      s[i+1] = '#';
      ct++;
    }
  }
  //#を.に変えるカウント                                                                                                                                                                                    
  for(int i=0;i<n;i++){
    if(c[i]=='#'){
      ct1++;
    }
  }

  for(int j=n-1;j>=0;j--){
    if(c[j]=='#'){
      ct1--;
    }else if(c[j]=='.'){
      break;
    }
  }

  if(ct1>=ct){
    cout << ct << endl;
  }else{
    cout << ct1 << endl;
  }



}