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 v1: usize = itr.next().unwrap().parse().unwrap();
    let v2: usize = itr.next().unwrap().parse().unwrap();
    let v3: usize = itr.next().unwrap().parse().unwrap();
    let v4: usize = itr.next().unwrap().parse().unwrap();

    let mut ans: usize = 99;
    for i in 1..31 {
        for j in i + 1..31 {
            for k in j + 1..31 {
                let mut dp: Vec<usize> = vec![99; 99];
                dp[i] = 1;
                dp[j] = 1;
                dp[k] = 1;
                for l in 1..31 {
                    dp[l + i] = std::cmp::min(dp[l + i], dp[l] + 1);
                }
                for l in 1..31 {
                    dp[l + j] = std::cmp::min(dp[l + j], dp[l] + 1);
                }
                for l in 1..31 {
                    dp[l + k] = std::cmp::min(dp[l + k], dp[l] + 1);
                }
                ans = std::cmp::min(ans, dp[v1] + dp[v2] + dp[v3] + dp[v4]);
            }
        }
    }
    println!("{}", ans);
}