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)

 int main() {
   int ablack=0,black=0;
  int  white=0,rwhite=0,rblack=0,sum=0,n,i;
   
   scanf("%d",&n);
   char s[n];
   scanf("%s",s);
  
   for(i=0;i<n;i++){
  if(s[i]=='.')rwhite++;
     if(s[i]=='#'){rwhite=0;ablack;}
   }
   n=n-rwhite;
       for(i=0;i<n;i++){
  if(s[i]=='.')rblack=0;
     if(s[i]=='#')rblack++;
   } 
     
   n=n-rblack;
   
    for(i=0;i<n;i++){
  if(s[i]=='.')white++;
     if(s[i]=='#')black++;
   }

   if(rblack>rwhite)
    sum=rwhite;
   else
     sum=rblack;
   
   if(black<white)
     sum=sum+black;
   else
     sum=sum+white;
   printf("%d",sum);
   return 0;
 }