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.Threading.Tasks;

namespace Miscelleneous {
	class Program {
		static int[] parins() {
			return Console.ReadLine().Split(' ').Select(s => int.Parse(s)).ToArray();
		}
		static void Main(string[] args) {
			Console.ReadLine();
			var S = Console.ReadLine();
			Console.WriteLine(calc(Parse(S)));
		}

		static bool[] Parse(string d) {
			return d.Select(c => c == '#').ToArray();
		}

		static int calc(bool[] Blacks) {
			bool flagAny = false;
			int count = 0;
			foreach (var black in Blacks) {
				if (!flagAny && black) flagAny = true;
				if (flagAny && !black) count++;
			}
			return count;
		}
	}

}