include iostream include algorithm include vector include cmath includ

#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <cstdio>
using namespace std;

struct pt
{
	double x, y;
	pt()
	{
		x = y = 0;
	}
	pt(double x_, double y_)
	{
		x = x_;
		y = y_;
	}
};

struct cir
{
	pt z;
	double r;
	cir()
	{
		z = pt();
		r = 0;
	}
	cir(pt z_, double r_)
	{
		z = z_;
		r = r_;
	}
};

vector <cir> ar;
int n;

double eps = 1e-8;
struct pare
{
	double y;
	int t;
	pare()
	{

	}
	pare(double y_, int t_)
	{
		y = y_;
		t = t_;
	}
	bool operator < (const pare& obj) const
	{	
		if (abs(y - obj.y) < eps)
		{
			return (t == -1 && obj.t == 1);
		}
		else
		{
			return y < obj.y;
		}

	}
};

vector <pare> line;

double f(double x_)
{
	line.clear();
	for (int i = 0; i < n; ++i)
	{
		double x = ar[i].z.x, y = ar[i].z.y, r = ar[i].r;
		if (fabs(x - x_) < r - eps)
		{
			double y1 = y + sqrt(r * r - (x - x_) * (x - x_));
			double y2 = y - sqrt(r * r - (x - x_) * (x - x_));
			line.push_back(pare(y2, 1));
			line.push_back(pare(y1, -1));
		}
	}
	sort(line.begin(), line.end());
	int lev = 0;
	double lasty = 0;
	double ans = 0;

	for (int i = 0; i < line.size(); ++i)
	{
		if (lev == 0)
		{
			if (line[i].t == 1)
			{
			lasty = line[i].y;
			}
		}

		lev += line[i].t;

		if (lev == 0)
		{
			if (line[i].t == -1)
			{
			ans += line[i].y - lasty;
			}
		}
	}
	return ans;
}

double integral(double a, double b)
{
	return (f(a) + f(b) + 4 * f((a + b) / 2)) * (b - a) / 6.0;
}

double simps(double a, double b)
{
	double mid = (a + b) / 2;
	double s1 = integral(a, b);
	double sl = integral(a, mid);
	double sr = integral(mid, b);
	if (fabs(s1 - sl - sr) > eps)
		return simps(a, mid) + simps(mid, b);
	else
		return s1;
}

int main()
{
	freopen("input.txt", "r", stdin);
	freopen("output.txt", "w", stdout);

	cin >> n;	
	line.reserve(2 * n);
	ar.resize(n);
	double a = 10005, b = -10005;

	for (int i = 0; i < n; ++i)
	{
		cin >> ar[i].z.x >> ar[i].z.y >> ar[i].r;
		a = min(a, ar[i].z.x - ar[i].r);
		b = max(b, ar[i].z.x + ar[i].r);
	}


	printf("%.5lf", simps(a, b));

	return 0;
}