using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
using System.Text;


class Program
{
    static void Main(string[] args)
    {
        // 入力
        //var s = Console.ReadLine();
        var n = long.Parse(Console.ReadLine());
        char[] s = Console.ReadLine().ToCharArray();

        var ans = long.MaxValue;

        long[] b = new long[n];
        long[] w = new long[n];
        if (s[0] == '.') w[0] = 1;
        if (s[0] == '#') b[0] = 1;
        for (int i = 1; i < n; i++)
        {
            if (s[i] == '.') w[i] = w[i - 1] + 1;
            else w[i] = w[i - 1];

            if (s[i] == '#') b[i] = b[i - 1] + 1;
            else b[i] = b[i - 1];
        }

        //ans = Math.Min(ans, w[n - 1]);
        //a//ns = Math.Min(ans, b[n - 1]);
        for (int i = 0; i < n; i++)
        {
            if(i != n - 1)var a = (b[n - i - 1]);
            if(i != 0)var c = (w[n - 1] - w[n - i - 1]);
            ans = Math.Min(ans, (b[n - i - 1]) + (w[n - 1] - w[n - i - 1]));
        }


        // 出力
        Console.WriteLine(ans);
    }
}