import java.util.ArrayDeque;
import java.util.Arrays;
import java.util.Scanner;

class Main {

	void run() {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		String S = sc.next();
		boolean[] a = new boolean[S.length()];
		for (int i = 0; i < S.length(); ++i) {
			a[i] = S.charAt(i) == '.';
		}
		int ans = solve(Arrays.copyOf(a, a.length), n);
		{
			int s = 0;
			int t = a.length - 1;
			while (s < t) {
				boolean tmp = a[s];
				a[s] = a[t];
				a[t] = tmp;
				++s;
				--t;
			}
			n = S.length() - n + 1;
		}
		ans = Math.min(ans, solve(a, n));
		System.out.println(ans);
	}

	int solve(boolean[] b, int n) {
		int ret = Integer.MAX_VALUE / 3;
		for (int j = 0; j < b.length - 1; ++j) {
			int cur = 0;
			boolean[] a = Arrays.copyOf(b, b.length);
			for (int k = j; k < b.length - 1; ++k) {
				a[k] = !a[k];
				++cur;
			}
			int t = a.length - 1;
			int s = 0;
			while (a[t])
				--t;
			while (a[s])
				++s;
			for (int i = n - 2; i >= s; --i) {
				a[i] = !a[i];
				++cur;
			}
			for (int i = s + 1; i <= t; ++i) {
				a[i] = !a[i];
				++cur;
			}
			ArrayDeque<Integer> dq = new ArrayDeque<>();
			for (int i = s; i <= t; ++i) {
				if (!a[i])
					dq.addLast(i);
			}
			while (!dq.isEmpty()) {
				if (dq.size() >= 2) {
					int u = dq.pollFirst();
					int v = dq.pollFirst();
					cur += (v - u) * 2;
				} else {
					cur = Integer.MAX_VALUE / 3;
					break;
				}
			}
			ret = Math.min(ret, cur);
		}
		return ret;
	}

	void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

	public static void main(String[] args) {
		new Main().run();
	}

}