use proconio::input;
fn main() {
    input!{
        n: usize,
        a: usize,
        b: usize,
    }
    let mut ans: usize = n + n/(lcm(a, b)) - n/a - n/b;
    println!("{}", ans)
}

fn gcd(a: usize, b: usize) -> usize{
    if b == 0{
        return a
    }
    gcd(b, a % b)
}

fn lcm(a: usize, b: usize) -> usize{
    a * b / gcd(a, b)
}