#include<iostream>
using namespace std;

int factorial(int x) {
	int result = 0;
	for (int i = 1; i <= x; i++) {
		result += i;
	}
	return result;
}

int main() {

	int input, temp1, temp2;
	input = temp1 = temp2 = 0;
	
	cin >> input;
	int* arr = new int[factorial(input)];
	for (int i = 0; i < factorial(input); i++) {
		cin >> arr[i];
	}

	int counter = 0;
	for (int i = input; i > 0; i--) {
		counter = factorial(i - 1);
		for (int j = 0; j < i - 1; j++) {
			if (arr[counter] > arr[counter + 1]) {
				arr[counter - i + 1] += arr[counter];
			}
			else {
				arr[counter - i + 1] += arr[counter + 1];
			}
			counter++;
		}
	}

	cout << arr[0] << endl;

	delete[] arr;
	return 0;
}