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>
#define ll long long
using namespace std;

bool cmp(int a,int b){
        return a>b;
}


int  main(){
    ios::sync_with_stdio(false);
    cin.tie(0);

    //Insert code

    ll n;
    cin>>n;
    string s;
    cin>>s;
    ll res=0;
    ll tmp=0,tmp2=0;
    for (ll i=n-1;i>=0 ;i--){
        
        if (s[i]=='#' && tmp==0){
          continue;
        }  
        if (s[i]=='.'){
            tmp++;
        }
        if (s[i]=='#' && tmp!=0){
            tmp2++;
        }
        if (tmp2!=0 && s[i-1]=='.'){
            res+=min(tmp,tmp2);
            tmp=0;
            tmp2=0;
        }
      // cout<<tmp<<" "<<tmp2<<endl; 
    }
        
     if (tmp!=0 && tmp2!=0){
            res+=min(tmp,tmp2);
            
        }

    cout<<res;
    //End code

    cerr << "\nTime elapsed: " << 1000*clock() / CLOCKS_PER_SEC << "ms\n";
    
}