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: Wrong Answer)

#include<stdio.h>
int main()
{
  int N,i,sum1=0,sum2=0,sum=0;
  
  scanf("%d\n", &N);
  
  char n[N], m[N];
  
  scanf("%s", n);
  for(i=0;i<N;i++){
  m[i]=n[i];
  }
  
 for(i=0;i<N;i++){
   if(n[i]=='#'){
     if(n[i+1]=='.'){
     n[i+1]='#';
     sum1++;
     }
   }
 }
  
  for(i=0;i<N;i++){
   if(m[i]=='#'){
     if(m[i+1]=='.'&&m[i-1]=='.'){
     m[i]='.';
     sum2++;
     }
   }
 }
  
  if(sum1<=sum2)sum=sum1;
  else sum=sum2;
  
  printf("%d", sum);
  return 0;
}