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 Rust (1.42.0) (judge verdict: Wrong Answer)

#[allow(unused_imports)]
use itertools::Itertools;
use proconio::input;
#[allow(unused_imports)]
use proconio::marker::*;

fn f(mut s: Vec<char>) -> usize {
    s.reverse();
    while matches!(s.last(), Some(&c) if c == '.') {
        s.pop();
    }
    s.iter().filter(|&c| *c == '.').count()
}
fn g(mut s: Vec<char>) -> usize {
    while matches!(s.last(), Some(&c) if c == '#') {
        s.pop();
    }
    s.iter().filter(|&c| *c == '#').count()
}

fn main() {
    input! {
        _n: usize,
        mut s: Chars,
    }

    println!("{}", std::cmp::min(f(s.clone()), g(s.clone())));
}