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

import javax.swing.JFrame;

public class Main {

	void run() {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] pf = new int[n];
		for (int i = 0; i < n; ++i) {
			pf[i] = sc.nextInt();
		}
		double[] F = new double[n + 1];
		double[] f = new double[n + 1];
		double F_inf = (Math.sqrt((0.81) / (1 - 0.81))) / ((0.9) / (1 - 0.9));
		for (int i = 1; i <= n; ++i) {
			double u = 0;
			double l = 0;
			for (int j = 1; j <= i; ++j) {
				u += Math.pow(0.81, j);
				l += Math.pow(0.9, j);
			}
			F[i] = Math.sqrt(u) / l;
			f[i] = (F[i] - F_inf) / (F[1] - F_inf) * 1200;
		}
		double u = 0, l = 0;
		for (int j = 1; j <= n; ++j) {
			u += Math.pow(2, 1d * pf[j - 1] / 800) * Math.pow(0.9, j);
			l += Math.pow(0.9, j);
		}
		System.out.println((int) (Math.log(u / l) / Math.log(2) * 800 - f[n]));
	}

	static void tr(Object... objects) {
		System.out.println(Arrays.deepToString(objects));
	}

	public static void main(String[] args) {
		new Main().run();
	}
}