import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;

public class No91 {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        List<Integer> l = new ArrayList<Integer>() {{
            add(s.nextInt());
            add(s.nextInt());
            add(s.nextInt());
        }};
        l.sort(Comparator.naturalOrder());
        while (l.get(2) - l.get(0) > 2) {
            l.set(2, l.get(2) - 2);
            l.set(0, l.get(0) + 1);
            l.sort(Comparator.naturalOrder());
        }
        System.out.println(l.get(0));
    }
}