#include <iostream>
#include <cmath>
using namespace std;

int main() {
	int p[12], e[12], sum, ef[12]; //p是花销，e是每个月剩下的钱

	for (int i = 0; i < 12; i++)
		cin >> p[i];

	e[0] = 300 - p[0];

	if (e[0] < 0) {
		cout << -1;
		return 0;
	}

	if (e[0] > 100) {
		ef[0] = e[0] % 100;

		sum += e[0] - ef[0];
	} else
		ef[0] = e[0];



	for (int i = 1; i < 12; i++) {

		e[i] = 300 - p[i] + ef[i - 1];

		if (e[i] < 0) {
			cout << (i + 1)*(-1);
			return 0;
		}

		if (e[i] > 100) {
			ef[i] = e[i] % 100;

			sum += e[i] - ef[i];
		} else
			ef[i] = e[i];
	}

	double sum1 = sum * 1.2;
	cout << sum1;

	return 0;
}