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++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

//confilm 0LL and 1LL
//confilm cornercases such as 0
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
using Vec = vector<ll>;
using VecP = vector<P>;
using VecB = vector<bool>;
using VecC = vector<char>;
using VecVec = vector<Vec>;
#define REP(i, m, n) for(ll (i) = (m); (i) < (n); ++(i))
#define REPN(i, m, n) for(ll (i) = (m); (i) <= (n); ++(i))
#define REPR(i, m, n) for(ll (i) = (m); (i) >= (n); --(i))
#define rep(i, n) REP(i, 0, n)
#define repn(i, n) REPN(i, 1, n)
#define repr(i, n) REPR(i, n, 0)
#define repnr(i, n) REPR(i, n, 1)
#define co(n) cout << (n) << endl
#define cosp(n) cout << (n) << ' '
#define setp(n) cout << fixed << setprecision(n);
#define all(s) (s).begin(), (s).end()
#define pb push_back
#define mp make_pair
#define mt make_tuple
#define fs first
#define sc second
template <typename T>
bool chmax(T &a, const T& b){if(a < b){a = b; return true;} return false;}
template <typename T>
bool chmin(T &a, const T& b){if(a > b){a = b; return true;} return false;}
void sonic(){ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);}
const ll INF = 1e9+1;
const ll LINF = 1e18+1;
const ll MOD = 1e9+7;
//const ll MOD = 998244353;
const double PI = acos(-1);
const double EPS = 1e-9;

int main(void){
	ll n;
	cin >> n;
	string s;
	cin >> s;
	bool flg = false;
	ll ans = 0;
	rep(i, n){
		if(s[i] == '.' && flg) ans++;
		else if(s[i] == '#') flg = true;
	}
	co(ans);

	return 0;
}