// Arup Guha
// 10/27/2013
// Solution to NCPC 2013 Problem J: Dartboard

import java.util.*;

public class dartboard {

	public static double var;

	// Precompute expectations for each area of the dartboard here.
	final static double[] expPts = {50, 25, 10.5, 31.5, 10.5, 21};

	public static void main(String[] args) {

		// Read in data.
		Scanner stdin = new Scanner(System.in);
		double[] radii = new double[7];
		for (int i=1; i<=6; i++)
			radii[i] = stdin.nextDouble();
		double stddev = stdin.nextDouble();
		var = stddev*stddev;

		// Add up expectation.
		double expect = 0;
		for (int i=0; i<6; i++)
			expect += (prob(radii[i], radii[i+1])*expPts[i]);
		System.out.println(expect);
	}

	// Integral of given function times area(2pir), used to evaluate probability.
	public static double f(double x) {
		return Math.exp(-x*x/(2*var));
	}

	// Probability between rings of radii r1 and r2
	public static double prob(double r1, double r2) {
		return f(r1) - f(r2);
	}
}