import core.bitop;
import std.algorithm;
import std.ascii;
import std.bigint;
import std.conv;
import std.functional;
import std.math;
import std.numeric;
import std.range;
import std.stdio;
import std.string;
import std.random;
import std.typecons;
import std.container;

alias sread = () => readln.chomp();
alias Point2 = Tuple!(long, "y", long, "x");

T lread(T = long)()
{
    return readln.chomp.to!T();
}

T[] aryread(T = long)()
{
    return readln.split.to!(T[])();
}

void scan(TList...)(ref TList Args)
{
    auto line = readln.split();
    foreach (i, T; TList)
    {
        T val = line[i].to!(T);
        Args[i] = val;
    }
}

void minAssign(T, U = T)(ref T dst, U src)
{
    dst = cast(T) min(dst, src);
}

enum MOD = 10 ^^ 9 + 7;

void main()
{
    long N = lread();
    string S = sread();
    long[] T = new long[N + 1];
    foreach (i; 0 .. N)
        T[i + 1] = T[i] + (S[i] == '#');
    // writeln(S);
    // writeln(T);

    long ans = long.max;
    foreach (i; 0 .. N)
    {
        long a = (T[i + 1]);
        long b = ((N - i - 1) - (T[$ - 1] - T[i]));
        // writefln("%d %d %d", i, a, b);
        ans = ans.min(a + b);
    }
    writeln(ans);
}
