#include <iostream>
#include <string>
#include <math.h>

using namespace std;

int main()
{
	int num;
	cin >> num;

	int sum = 0;
	int currentNumber;

	for (int i = 1; i <= num; i++)
	{
		cin >> currentNumber;
		sum = currentNumber + currentNumber;
	}
	cout << sum << endl;


	return 0;
}