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, i=0, ans=0, cntd=0, cnts=0, f=0;
    char s[10*10*10*10*10*10];
    scanf("%d", &n);
    scanf("%s", s);
    while(s[i]!='\0'){
        if(s[i]=='#' && f==0) cnts++;
        if(s[i]=='.' && f==1) cntd++; 
        if(s[i]=='#' && s[i+1]=='.'){
            f=1;
        }
        if(f==1 && s[i]=='#'){
            if(cntd>cnts) ans=ans+cnts+1;
            else ans=ans+cntd+1;
            f=0;
            cntd=0;
            cnts=0;
        }
        i++;
    }

    printf("%d\n", ans);
    return 0;
}