#include <iostream>
#include <vector>
#include <algorithm>
#include <cmath>

using namespace std;

int n;
double eps = 1e-9;
struct Circle
{
	int x;
	int y;
	int r;
};
vector<Circle> v(50);
vector<pair<double, bool> > q;
double F(double x)
{
	q.clear();
	pair<double, bool> temp;
	for (int i = 0; i < n; i++)
	{
		if (fabs(x - v[i].x) < v[i].r)
		{
			temp.first = -sqrt(v[i].r*v[i].r - (v[i].x - x)*(v[i].x - x)) + v[i].y;
			temp.second = true;
			q.push_back(temp);
			temp.first = sqrt(v[i].r*v[i].r - (v[i].x - x)*(v[i].x - x)) + v[i].y;
			temp.second = false;
			q.push_back(temp);
		}
	}
	sort(v.begin(), v.end());
	int rang = 0;
	double l, s = 0;
	for (int i = 0; i < q.size(); i++)
	{

		if (q[i].second)
		{
			if (rang == 0)
				l = q[i].first;
			rang++;
		}
		else rang--;

		if (i != 0 && rang == 0)
		{
			s += q[i].first - l;
		}
	}
	return s;
}

double S(double a, double b)
{
	return (F(a) + F(b) + 4 * F((a + b) / 2))*(b - a) / 6;
}

double Square(double a, double b)
{
	double mid = (a + b) / 2;
	if (fabs(S(a, b) - (S(a, mid) + S(mid, b))) < eps)
		return S(a, b);
	else
		return (S(a, mid) + S(mid, b));
}
int main()
{
	cin >> n;
	Circle temp;
	double l, r;
	cin >> v[0].x >> v[0].y >> v[0].r;
	l = v[0].x - v[0].r;
	r = v[0].x + v[0].r;
	for (int i = 1; i < n; i++)
	{
		cin >> v[i].x >> v[i].y >> v[i].r;
		if (v[i].x - v[i].r < l)
			l = v[i].x - v[i].r;
		if (v[i].x + v[i].r > r)
			r = v[i].x + v[i].r;

	}
	cout << Square(l, r) << endl;
	return 0;

}