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 Go (1.6) (judge verdict: Wrong Answer)

package main

import (
	"fmt"
	"strings"
)

func Solve(s string) int {
	var n int
	for i := 0; i <= len(s); i++ {
		a := strings.Count(s[:i], "#")
		b := strings.Count(s[i:], ".")
		if c := a + b; n == 0 || n > c {
			n = c
		}
	}
	return n
}

func main() {
	var n int
	fmt.Scanf("%d", &n)
	var s string
	fmt.Scanf("%s", &s)
	result := Solve(s)
	fmt.Println(result)
}