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(){
    long N;
    scanf("%ld", &N);
    char S[N+1];
    scanf("%s", S);
    S[N] = '\0';
    long cnt = -1;
    for(long i=0;i<N;i++){
        if(S[i]=='#'){
            cnt = i;
            break;
        }
    }
    long ans = 0;
    for(long i=cnt;i<N;i++){
        if(S[i] == '.'){
            ans ++;
        }
    }
    if(cnt == -1){
        ans = 0;
    }
    if(ans > N/2){
        ans = N - ans;
    }
    printf("%ld\n", ans);
    return 0;
}