#include <bits/stdc++.h>
using namespace std;

using uint = unsigned int;
using ld = long double;
const uint INF = ~0;
const ld eps = 1e-9;

uint Rand () {
	mt19937_64 rnd(random_device{}());
	return rnd();
}
ld rand_x () {
	ld x = Rand();
	x = x * 2 / INF;
	return x;
}
ld rand_theta () {
	ld theta = Rand();
	theta = theta / INF * acos(0);
	return theta;
}

int main () {
	int step = 100000;
	int cnt = 0;
	for (int i = 1; i <= step; i ++) {
		ld x = rand_x();
		ld theta = rand_theta();
//		cout << x << ' ' << theta << ' ' << x + sin(theta) << endl;
		if (x + sin(theta) - 2.0 > eps) cnt ++;
	}
	ld pi = (ld)step / cnt;
	cout << fixed << setprecision(9) << pi << endl;
}