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 Kotlin (1.0.0) (judge verdict: Wrong Answer)

import java.util.*
import java.math.*
fun main(args: Array<String>) {

    val N = readLine()!!.toInt()
    var ansb = 0
    var answ = 0
    var isBlack = false;
    var isWhite = false;
    var tmpb = 0
    for (c in readLine()!!) {
        if (c == '#') {
            tmpb++
            isBlack = true
        }
        if (c == '.') {
            if (isBlack) ansb++
            answ += tmpb
            tmpb = 0
        }
    }

    println(Math.min(ansb,answ));
}