use std::io::Read;
fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&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 dp: Vec<f32> = vec![20200.0; 20200];
    dp[h] = 0.0;
    for i in (0..h + 1).rev() {
        if dp[i] != 20200.0 {
            if i >= a {
                if dp[i - a] > dp[i] + 1.0 {
                    dp[i - a] = dp[i] + 1.0;
                }
            } else {
                if dp[0] > dp[i] + 1.0 {
                    dp[0] = dp[i] + 1.0;
                }
            }
            if i >= d {
                if dp[i - d] > dp[i] + 3.0 / 2.0 {
                    dp[i - d] = dp[i] + 3.0 / 2.0;
                }
            } else {
                if dp[0] > dp[i] + 3.0 / 2.0 {
                    dp[0] = dp[i] + 3.0 / 2.0;
                }
            }
        }
    }
    println!("{0:.4}", dp[0]);
}