const INF: isize = 1isize << 60;

fn main() {
    let mut t = String::new();
    std::io::stdin().read_line(&mut t).ok();
    let t: isize = t.trim().parse().unwrap(); 
    let mut xa = String::new();
    std::io::stdin().read_line(&mut xa).ok();
    let xa: Vec<isize> = xa.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let x = xa[0];
    let a = xa[1];
    let mut ya = String::new();
    std::io::stdin().read_line(&mut ya).ok();
    let yb: Vec<isize> = ya.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let y = yb[0];
    let b = yb[1];

    let mut result = INF;
    let offset = if t < 0 { t.abs() / b + if t % b != 0 { 1 } else { 0 } } else { 0 };
    let offset_dates = offset * y;
    let t = t + offset * b;
    for i in 0..=10000000 {
        let mut cost = offset_dates + i*y;
        let t = t + i*b;
        cost += t / a * x;
        let t = t % a;
        cost += t;
        result = result.min(cost);
    }
    println!("{}", result);
}