#include <bits/stdc++.h>

#define y1 __zzd12323

using namespace std;

const int N=1005;

const double Eps=1e-9,INF=1e9;

double sqr(double x){

	return x*x;

}

int n;

struct Circle{

	double x,y,r;

}c[N],_c[N];

bool cmpr(Circle a,Circle b){

	return a.r>b.r;

}

struct Seg{

	double L,R;

}s[N];

bool cmp(Seg a,Seg b){

	return a.L<b.L;

}

double F(double x){

	int m=0;

	for (int i=1;i<=n;i++){

		if (fabs(x-c[i].x)>c[i].r-Eps)

			continue;

		double M=c[i].y,a=sqrt(sqr(c[i].r)-sqr(x-c[i].x));

		s[++m].L=M-a,s[m].R=M+a;

	}

	sort(s+1,s+m+1,cmp);

	double res=0.0,mx=-INF;

	for (int i=1;i<=m;i++)

		if (s[i].L>mx)

			res+=s[i].R-s[i].L,mx=s[i].R;

		else if (s[i].R>mx)

			res+=s[i].R-mx,mx=s[i].R;

	return res;

}

double Simpson(double a,double b,double Fa,double Fb,double Fab){

	return (b-a)/6*(Fa+Fab*4+Fb);

}

double Asr(double a,double b,double v,double Fa,double Fb,double Fab){

	double ab=(a+b)/2;

	double LFab=F((a+ab)/2),L=Simpson(a,ab,Fa,Fab,LFab);

	double RFab=F((ab+b)/2),R=Simpson(ab,b,Fab,Fb,RFab);

	if (fabs(v-L-R)<Eps)

		return v;

	return Asr(a,ab,L,Fa,Fab,LFab)

	      +Asr(ab,b,R,Fab,Fb,RFab);

}

int killed[N];

double Dis(double x1,double y1,double x2,double y2){

	return sqrt(sqr(x1-x2)+sqr(y1-y2));

}

int main(){

	scanf("%d",&n);

	double a=INF,b=-INF;

	for (int i=1;i<=n;i++){

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

		a=min(a,c[i].x-c[i].r);

		b=max(b,c[i].x+c[i].r);

	}

	sort(c+1,c+n+1,cmpr);

	for (int i=1;i<=n;i++)

		for (int j=i+1;j<=n;j++)

			if (Dis(c[i].x,c[i].y,c[j].x,c[j].y)+c[j].r<c[i].r+Eps)

				killed[j]=1;

	int _n=0;

	for (int i=1;i<=n;i++)

		if (!killed[i])

			c[++_n]=c[i];

	n=_n;

	double ans=0;

	for (double x=a;x<b;x++){

		for (int i=1;i<=n;i++)

			_c[i]=c[i];

		int _n=n;

		n=0;

		for (int i=1;i<=_n;i++)

			if (c[i].x-c[i].r<i+1&&c[i].x+c[i].r>i)

				c[++n]=_c[i];

		n=_n;

		for (int i=1;i<=n;i++)

			c[i]=_c[i];

		double Fa=F(x),Fb=F(x+1),Fab=F((x+x+1)/2);

		ans+=Asr(x,x+1,Simpson(x,x+1,Fa,Fb,Fab),Fa,Fb,Fab);

	}

	printf("%.3lf",ans);

	return 0;

}