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

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