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(void){
  int n,count = 0,count1 = 0;
  
  scanf("%d",&n);
  char s;
  int flag[n];
  int i;
  int u = 0;
  
  for(i = 0;i < n;i++){
   scanf(" %c",&s);
    if(s == '#'){
     flag[i] = 1;
      u++;
    }else{
     flag[i] = 0;
    }
  }
  
  for(i = 0;i < n;i++){
    if(flag[i] == 1){
      break;
    }
  }
  
  for(int m = i;m < n;m++){
    if(flag[m] == 0){
      count++;
    }
  }
  
  if(flag[n-1] == 1){
    u--;
  }
  
  if(count < u){
  printf("%d\n",count);
  }else{
   printf("%d\n",u);
  }
  
  return 0;
}