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# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
using System.IO;
using static System.Console;
using static System.Math;

namespace AtCodeeeer
{
    class AtCOOOOOOOOOOOder
    {
        static void Main(string[] args)
        {
            int N = int.Parse(ReadLine());
            var s = ReadLine();

            int ans = int.MaxValue;
            //iが境界線,iより左が全部".",右は"#"
            for (int i = 0; i < N; i++)
            {
                int tmp = 0;
                for (int j = 0; j < N; j++)
                {
                    if (j<=i && s[j] == '#')
                    {
                        tmp++;
                    }
                    if (j>i && s[j] == '.')
                    {
                        tmp++;
                    }
                }
                ans = Min(ans, tmp);
            }
            WriteLine(ans);
        }
    }
}