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: Runtime Error)

#include <stdio.h>

int main(int argc, const char * argv[]) {
    
    unsigned int n=0,i=0,j=0,cnt1=0,cnt2=0;
    scanf("%u",&n);
    char s[2*100000];
    scanf("%s",s);
    while(s[j] == '.'){
        j++;
    }
    while(s[n-1] == '#'){
      n = n-1;
    }
    cnt2++;
    
    for(i=j+1;i<n;i++){
        if(s[i] == '#'){
            cnt2++;
        }else if(s[i] =='.'){
            cnt1++;
        }
    }
    if(cnt1 < cnt2){
        printf("%u",cnt1);
    }else{
        printf("%u",cnt2);
    }
    
    return 0;
}