#include <bits/stdc++.h>
 
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define rep(i, n)  for(int i=0;i<(n);++i)
#define REPr(i, n) for(int i=(n)-1;i>=0; --i)
#define FORq(i, m, n) for(int i = (m);i <= (n);++i)
#define FORqr(i, m, n) for(int i = (n);i >=(m);--i)
#define PB push_back
#define MP make_pair
#define DEBUG printf("%s\n","debug")
#define fst first
#define snd second
#define SIN(x, S) (S.count(x) != 0)
#define M0(x) memset(x,0,sizeof(x))
#define FILL(x, y) memset(x,y,sizeof(x))
#define MM(x) memset(x,-1,sizeof(x))
#define ALL(x) (x).begin(),(x).end()
using namespace std;
typedef pair<int, int> PII;
typedef pair<long long, long long> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<long long> VL;
typedef long long ll;
typedef long long integer;
///////////////////////////////////////////////
/* (๑╹◡╹) */
ll gcd(ll x, ll y) { return y ? gcd(y, x % y) : x; }
ll MOD = 1000000007;
template<class T>
inline bool chmin(T &a, T b) {
	if (a > b) {
		a = b;
		return true;
	}
	return false;
}
 /* (๑╹◡╹)(๑╹◡╹)(๑╹◡╹)*/
template<class T>
inline bool chmax(T &a, T b) {
	if (a < b) {
		a = b;
		return true;
	}
	return false;
}
/* (๑╹◡╹)(๑╹◡╹)(๑╹◡╹)(๑╹◡╹)(๑╹◡╹)(๑╹◡╹) */
///////////////////////////////////////////////
const int MAX = 510000;

long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
    fac[0] = fac[1] = 1;
    finv[0] = finv[1] = 1;
    inv[1] = 1;
    for (int i = 2; i < MAX; i++){
        fac[i] = fac[i - 1] * i % MOD;
        inv[i] = MOD - inv[MOD%i] * (MOD / i) % MOD;
        finv[i] = finv[i - 1] * inv[i] % MOD;
    }
}

// 二項係数計算
long long COM(int n, int k){
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
 



int main() {
	int ans = -1;
	int N; cin >> N;
	string S; cin >> S;

	int b[N+2] = {};//i以下に存在する黒石の数
	int w[N+2] = {};//i以上に存在する白石の数
	int a = 0;
	for (int i = 1; i <= N; i++)
	{
		if(S[i] == '#'){a++;}
		b[i]=a;
	}
	a = 0;
	for (int i = N; 0 < i; i--)
	{
		if(S[i] == '.'){a++;}
		w[i] = a;
	}

	for (int i = 0; i <= N; i++)
	{
		int n_ans = b[i] + w[i+1];
		if(ans == -1 or n_ans < ans){ans = n_ans;}
	}
	//ans = min(abs(b[N-1]-N),ans);//全てを黒で塗るケース
	//ans = min(abs(w[0]-N),ans);//全てを白で塗るケース
	

	cout << ans << endl;
	}
