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;
    scanf("%d",&N);
    char S[N];
    scanf("%s",S);
    int kuro = 0;
    int siro = 0;
    int min = 0;
    if(S[N-1]=='#'){
        if(S[0]=='#'){
            kuro ++;
        }
        for(int i=1;i<N-1;i++){
            if(S[i]=='#'){
                kuro ++;
            }else if(S[i]=='.'){
                siro ++;
            }
        }
        if(kuro<siro){
            min = kuro;
        }else{
            min = siro;
        }
    }else{
        for(int i=0;i<N;i++){
            if(S[i]=='#'){
                kuro ++;
            }else if(S[i]=='.'){
                siro ++;
            }
        }
        if(kuro<siro){
            min = kuro;
        }else{
            min = siro;
        }
        kuro = 0;
        siro = 1;
        for(int i=1;i<N-1;i++){
            if(S[i]=='#'){
                kuro ++;
            }else if(S[i]=='.'){
                siro ++;
            }
        }
        if(siro < min){
            min = siro;
        }
        if(kuro < min){
            min = kuro;
        }

    }
    printf("%d",min);
    return 0;
}