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)

#include <bits/stdc++.h>
using namespace std;
typedef long long int ll;
#define inf 1e16
#define MOD 1e9+7
#define gcd __gcd //最大公約数,gcd(x,y)
int lcm(int a, int b){return a/gcd(a, b)*b;} //(int)最小公倍数,lcm(x,y)
ll llcm(ll a, ll b){return a/gcd(a, b)*b;}//(ll)最小公倍数,lcm(x,y)


int main(){
  int N,i,sh=0,dot=0;
  string S;
  cin >> N >> S;

  for(i=0 ; i<N ; i++){
    if(S[i] == '.'){
      dot++;
    }else{
      sh++;
    }
  }
  if((sh == 0)||(dot == 0)){
    cout << "0" << endl;
  }else{
    cout << min(sh,dot) << endl;
  }


}