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: Runtime Error)

#include <iostream>
#include <string>
#include <cstdio>
#include <algorithm>
#include <functional>
#include <math.h>
using namespace std;
int main(){

	int N;
	string S;
	cin >> N;
	cin >> S;
	string str[N];
	for(int i = 0; i < N; i++){
		str[i] = S.substr(i,1);
	}
	int ans = 0;
	string stra[N];
	for(int m = 0; m < N; m++){
		stra[m] = str[m];
	}
	for(int j = 0; j < N-1; j++){
		if(stra[j] == "#" && stra[j + 1] == "."){
			stra[j + 1] = "#";
			ans++;
		}
	}
	int ansbetu = 0;
	for(int k = N; k >= 1; k--){
		if(str[k] == "." && str[k - 1] == "#"){
			str[k-1] = ".";
			ansbetu++;
		}
	}
	if(ans > ansbetu){
		cout << ansbetu << endl;
	}
	else{
		cout << ans << endl;
	}


}