Background

Because the oier tried to hack lhd's code yesterday,but the oier failed.So lhd cook the oier,and call everyone to have a party.

Description

To cook the oier,level of attainmen must be:

$$x=\frac{\sin A+\sin B+\sin C}{\cos\frac{A}{2}\cos\frac{B}{2}\cos\frac{C}{2}}*\sum_{i=0}^{\infty} \frac{e^{i\pi}e^{i\pi}}{4i+1}-\frac{\sin A+\sin B+\sin C}{\cos\frac{A}{2}\cos\frac{B}{2}\cos\frac{C}{2}}*\sum_{i=1}^{\infty} {\frac{e^{i\pi}e^{i\pi}}{4i-1}} $$

That right,it's a irrational number.

A,B,C is the horn of the table,because if we think the table in the calculate of attainmen,the meals will be delicious.

We know, we need a pot,too:

But lhd think the fire is little bit small,so he add the level of attainmen,like this:

$$(2x+\sum_{i=1}^n a_i*x)3x^2$$

Also,we need think of pot:

$$\frac{(2x+\sum_{i=1}^n a_i*x)3x^2}{(\frac{C}{d})^3} $$

OK,we can use the level of attainmen up to cook a wonderful oier.But lhd want you to say the level of attainmen,that he would give you the meals.

Input Format

In the first line,There is one number $d$

In the second line,There is one number$n$.

In the third line,There are $n$ number，The $i-th$number mean $a_i$.

Output Format

A num,mean level of attainmen.

Samples

9109823
10
1 2 3 4 5 6 7 8 9 10

171

Tips

$1\le n,a_i \le 4*10^4,1\leq d \leq 10^9$

Fun Thing

lhd have a big big big big pot,right?