import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int[] value = new int[4];
        for (int i = 0; i < 4; i++) {
            value[i] = sc.nextInt();
        }
        int min = Integer.MAX_VALUE;
        for (int a = 30; a >= 3; a--) {
            for (int b = a - 1; b >= 2; b--) {
                for (int c = b - 1; c >= 1; c--) {
                    int[] counts = new int[31];
                    Arrays.fill(counts, Integer.MAX_VALUE / 10);
                    counts[0] = 0;
                    for (int i = 0; i + a <= 30; i++) {
                        counts[i + a] = Math.min(counts[i + a], counts[i] + 1);
                    }
                    for (int i = 0; i + b <= 30; i++) {
                        counts[i + b] = Math.min(counts[i + b], counts[i] + 1);
                    }
                    for (int i = 0; i + c <= 30; i++) {
                        counts[i + c] = Math.min(counts[i + c], counts[i] + 1);
                    }
                    int sum = 0;
                    for (int x : value) {
                        sum += counts[x];
                    }
                    min = Math.min(min, sum);
                }
            }
        }
        System.out.println(min);
    }
}
class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        if (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}