fn main() { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); let mut itr = s.trim().split_whitespace(); let h: usize = itr.next().unwrap().parse().unwrap(); let a: usize = itr.next().unwrap().parse().unwrap(); let d: usize = itr.next().unwrap().parse().unwrap(); let mut ans = h as f64; for i in 0..=h / a + 1 { let mut x = h - i * a; let mut y = i as f64; if x > 0 { let z = (x + d - 1) / d; y += z as f64 * 1.5; } if y < ans { ans = y; } } println!("{}", ans); }