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>
#define max(x,y) ((x)>(y)?(x):(y))
#define min(x,y) ((x)<(y)?(x):(y))
#define FOR(i,m,n) for(i=m;i<n;i++)

int main(void)
{
	long long a,b=0,c=0,e=0,f=0,g=0,h=0,i;
	char d[1000010];
	scanf("%lld",&a);
	scanf("%s",d);
	for(i=0;i<a;i++){
		if(d[i]=='.'){
			b++;
		}else{
			c++;
		}
	}
	for(i=a-1;i>=0;i--){
		if(d[i]=='.') e=1;
		if(e==1){
			if(d[i]=='#') f++;
		}
	}
	for(i=0;i<a;i++){
		if(d[i]=='#') g=1;
		if(g==1){
			if(d[i]=='.') h++;
		}
	}
	printf("%lld\n",min(f,min(b,min(c,h))));
	return 0;
}