fn main() {
    let mut ngv = String::new();
    std::io::stdin().read_line(&mut ngv).ok();
    let ngv: Vec< u128> = ngv.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let n = ngv[0];
    let g = ngv[1];
    let v = ngv[2];

    if n / 5 * g % v == 0 {
        println!("{}", n / 5 * g / v);
    } else {
        println!("{}.{}", n / 5 * g / v,  n / 5 * g % v * 1_000_000_000_000_000_000 / v);
    }
}