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>
#include <string.h>

int main(){
	int N,count1=0,count2=0;
	char S[200001];
	scanf("%d",&N);
	scanf("%s",S);
	
	for(int i=0;i<N;i++){
		if(S[i]=='#'){
			count1++;
		}else{
			count2++;
		}
	}
	for(int i=0;i<N;i++){
		if(S[i] == '#')break;
		count2--;
	}
	if(count2>count1){
		printf("%d\n",count1);
	}else{
		printf("%d\n",count2);
	}
	return 0;
}