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<sstream>
#include<fstream>
#include<string>
#include<vector>
#include<deque>
#include<queue>
#include<stack>
#include<set>
#include<map>
#include<algorithm>
#include<functional>
#include<utility>
#include<bitset>
#include<cmath>
#include<cstdlib>
#include<ctime>
#include<cstdio>

using namespace std;

#define REP(i,n) for(int i=0;i<int(n);i++)
#define foreach(c,itr) for(__typeof((c).begin()) itr=(c).begin();itr!=(c).end();itr++)
typedef long long ll;
typedef pair<int,int> P;

int main(void){
	          int i;

	          cin.tie(0);  ios_base::sync_with_stdio(false);

	          int N;
	          string S;
	          cin >> N >> S;

	          if(N==1){
	        	  cout << 0 << endl;
	        	  return 0;
	          }

	          int p=-1;
	          for(i=0;i<N;i++){
	        	  if(S[i]=='#'){
	        		  p=i;
	        		  break;
	        	  }
	          }

	          if(p==-1 || p==N-1){
	        	  cout << 0 << endl;
	        	  return 0;
	          }

	          int b=0,w=0;
	          for(i=p;i<N;i++){
	        	  if(S[i]=='#') b++;
	        	  else w++;
	          }

	          cout << min(b,w) << endl;


	          return 0;
}