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;
	int kuro=0,siro=0,ans;
	char input;
	if(scanf("%d ",&n)!=1)return 1;
	while(kuro+siro<n){
		//if(scanf("%c",&input)!=1)return 1;
		input=getc(stdin);
		if(input=='#'){
			kuro++;
		}else if(input=='.'){
			siro++;
		}
	}
	if(siro<kuro){
		ans=siro;
	}else{
		ans=kuro;
	}
	printf("%d\n",ans);
	return 0;
}