import java.util.ArrayList;
import java.util.HashSet;
import java.util.Scanner;

public class Largest3Rectangles {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        String s = input.nextLine();
        s = s.replace("x", "");
        String[] recsstr = s.split("[\\[\\] \\s]");
        int bestarea = 0;
        int[] numbers = new int[recsstr.length];
        ArrayList<Integer> areas = new ArrayList<Integer>();
        for (int i = 0; i < recsstr.length; i++) {
            numbers[i] = Integer.parseInt(recsstr[i]);

        }
        for (int i = 0; i < numbers.length - 1; i += 2) {
            int area = numbers[i] * numbers[i+1];

        }
        for (int i = 0; i < areas.size()-2; i++) {
            int nowarea = areas.get(i) + areas.get(i+1) + areas.get(i+2);
            if(nowarea > bestarea){
                bestarea = nowarea;
            }
        }

        System.out.println(bestarea);
    }
}