import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[] arr = new int[3];
        for (int i = 0; i < 3; i++) {
            arr[i] = sc.nextInt();
        }
        int left = 0;
        int right = Integer.MAX_VALUE / 10;
        while (right - left > 1) {
            int m = (left + right) / 2;
            int minus = 0;
            int plus = 0;
            for (int i = 0; i < 3; i++) {
                if (arr[i] < m) {
                    minus += m - arr[i];
                } else {
                    plus += (arr[i] - m) / 2;
                }
            }
            if (plus >= minus) {
                left = m;
            } else {
                right = m;
            }
        }
        System.out.println(left);
    }
}