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;

#define fore(i, s, e) for(int i = s; i < e; i++)
#define FIN ios::sync_with_stdio(0); cin.tie(0); cout.tie(0)
#define pb push_back
#define fst first
#define snd second

typedef long long ll;

int main() {
    int n; cin >> n;
    string s; cin >> s;
    int i = 0;
    while(i < n && s[i] == '.') i++;
    int j = n;
    while(j > 0 && s[j - 1] == '#') j--;
    int a = 0, b = 0; 
    while(i < j) {
        a += s[i] == '.';
        b += s[i] == '#';
        i++;
    }
    cout << min(a, b) << endl;
    return 0;
}