fn main() {
    let _: u32 = read();
    let s: String = read();

    let cs = s.chars().collect::<Vec<char>>();

    let mut flag = false;
    let mut counter: u64 = 0;

    for c in cs.clone() {
        // # が出るまで送る
        match (flag, c) {
            (false, '.') => { continue; },
            (false, '#') => { flag = true; },
            (true, '.') => {counter += 1;}
            _ => {}
        }
    }

    flag = false;
    let mut counter2: u64 = 0;
    for c in cs.iter().rev() {
        // . が出るまで送る
        match (flag, c) {
            (false, '#') => { continue; },
            (false, '.') => { flag = true; },
            (true, '#') => {counter2 += 1;}
            _ => {}
        }
    }

    println!("{}", 
        if counter > counter2 {
            counter2
        } else {
            counter
        }
    );

}

#[warn(dead_code)]
fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[warn(dead_code)]
fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().split_whitespace()
        .map(|e| e.parse().ok().unwrap()).collect()
}

#[warn(dead_code)]
fn read_mat<T: std::str::FromStr>(row: u32) -> Vec<Vec<T>> {
    let mut vec = Vec::new();

    for _i in 0..row {
        vec.push(read_vec::<T>());
    }

    vec
}