fn main() {
    let mut temp = String::new();
    std::io::stdin().read_line(&mut temp).ok();
    let temp: Vec<usize> = temp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let mut n = temp[0];
    let m = temp[1];
    let p = temp[2]-1;
    let q = temp[3]-1;

    let mut result = 0usize;
    while n > 0 {
        if p <= result % 12 && result % 12 <= p+q {
            n -= (m*2).min(n);
        } else {
            n -= m.min(n);
        }
        result += 1;
    }
    println!("{}", result);
}