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 (GCC 5.4.1) (judge verdict: Runtime Error)

#include <stdio.h>

int main()
{
  int n, i=0, w=0, b=0, max=0, ans, tmp=0;
  char s[n];

  scanf("%d",&n);
  scanf("%s",s);

  while(s[i]='.'){
    i++;
  }
  
  for(i;i<n;i++){
    if(s[i]=='#'){
      b=b+1;
    }
    else{
      w=w+1;
    }
    if(b=w){
      max=i+1;
      tmp=b;
    }
  }
  
  b=0;w=0;
  for(i=max;i<n;i++){
    if(s[i]='#'){
      b=b+1;
    }
    else{
      w=w+1;
    }
  }

  if(b>w){
    ans=w+tmp;
  }
  else{
    ans=b+tmp;
  }

  printf("%d",&ans);

  return 0;
}