#include<cstdio>

#include<cstring>

#include<cmath>

#include<iostream>

#include<algorithm>

#include<queue>

using namespace std;

const double eps = 1e-;

const double PI = acos(-1.0);

const double INF = 1000000000000000.000;

struct Point{

    double x,y;

    Point(double x=, double y=) : x(x),y(y){ }    //构造函数

};

typedef Point Vector;

struct Circle{

     Point c;

     double r;

     Circle() {}

     Circle(Point c,double r): c(c),r(r) {}

};

Vector operator + (Vector A , Vector B){return Vector(A.x+B.x,A.y+B.y);}

Vector operator - (Vector A , Vector B){return Vector(A.x-B.x,A.y-B.y);}

Vector operator * (double p,Vector A){return Vector(A.x*p,A.y*p);}

Vector operator / (Vector A , double p){return Vector(A.x/p,A.y/p);}

bool operator < (const Point& a,const Point& b){

    return a.x < b.x ||( a.x == b.x && a.y < b.y);

}

int dcmp(double x){

    if(fabs(x) < eps) return ;

    else              return x <  ? - : ;

}

bool operator == (const Point& a, const Point& b){

    return dcmp(a.x - b.x) ==  && dcmp(a.y - b.y) == ;

}

///向量（x,y）的极角用atan2(y,x);

inline double Dot(Vector A, Vector B){ return A.x*B.x + A.y*B.y; }

inline double Length(Vector A)    { return sqrt(Dot(A,A)); }

inline double Angle(Vector A, Vector B)  { return acos(Dot(A,B) / Length(A) / Length(B)); }

double Cross(Vector A, Vector B)  { return A.x*B.y - A.y * B.x; }

Point read_point(){

    Point A;

    scanf("%lf %lf",&A.x,&A.y);

    return A;

}

/*************************************分 割 线*****************************************/

const int maxn = ;

Circle C[maxn];

int main()

{

    //freopen("E:\\acm\\input.txt","r",stdin);

    int N;

    cin>>N;

    for(int i=;i<=N;i++){

        scanf("%lf %lf %lf",&C[i].c.x,&C[i].c.y,&C[i].r);

    }

    double cnt = ;

    for(double x = 0.000;x<=1.000;x+=0.001)

        for(double y = 0.000;y<=1.000;y+=0.001){

            Point A = Point(x,y);

            for(int i=;i<=N;i++){

                if(dcmp(Length(A-C[i].c)-C[i].r) < ){

                    cnt ++;

                    break;

                }

            }

    }

    double prec = cnt/1e6;

    cout<<prec*<<endl;

}