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![0.0; 100010];
    dp[0] = 0.0;
    for i in 0..h + 1 {
        let mut res1: f32 = 1.0;
        let mut res2: f32 = 3.0 / 2.0;
        if i > a {
            res1 += dp[i - a];
        }
        if i > d {
            res2 += dp[i - d];
        }
        if res1 > res2 {
            dp[i] = res2;
        } else {
            dp[i] = res1;
        }
    }
    println!("{0:.4}", dp[h]);
}