package p03_Arrays.Lab;

import java.util.Arrays;
import java.util.Scanner;

public class P07_CondenseArrayToNumber {
    public static void main(String[] args) {
        Scanner console = new Scanner(System.in);
        int[] nums = Arrays.stream(console.nextLine().split(" "))
                .mapToInt(Integer::parseInt).toArray();

        int[] condensed = new int[nums.length - 1];

        for (int i = 0; i < condensed.length; i++) {
            nums = condensed(nums);
        }

        System.out.println(nums[0]);

    }


    private static int[] condensed(int[] nums) {
        int[] condensed = new int[nums.length - 1];
        for (int i = 0; i < condensed.length; i++) {
            condensed[i] = nums[i] + nums[i + 1];
        }
        return condensed;
    }
}