import static java.lang.Math.sqrt;

public class Ohjelma {

    public static void main(String[] args) {
        double a = sqrt(2);
        double b = 0;
        double p = 2 + sqrt(2);

        for (int i = 0; i < 10; i++) {
            double an1 = (sqrt(a) + 1 / sqrt(a)) / 2;
            double bn1 = ((1 + b) * sqrt(a)) / (a + b);
            double pn1 = ((1 + an1) * p * bn1) / (1 + bn1);

            a = an1;
            b = bn1;
            p = pn1;
        }

        System.out.println(p);
    }
}