#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define N 2003
#define eps 1e-13
using namespace std;
int n,m,top,st,ed;
bool mark[N];
double xl[N],xr[N],ans;
struct data{double x,y,r;}a[N],sk[N]; 
struct line{double l,r;}p[N];
int cmp(data a,data b){return a.r<b.r;}
int cmp1(data a,data b){return a.x-a.r<b.x-b.r;}
int cmp2(line a,line b){return a.l<b.l;}
double pow(double x){return x*x;}
double dis(data a,data b){return sqrt(pow(a.x-b.x)+pow(a.y-b.y));}
double getf(double x)
{
    double r,dis,len=0;
    int sz=0;
    for (int i=st;i<=ed;i++){
        if (xl[i]>=x||xr[i]<=x) continue;
        dis=sqrt(sk[i].r-pow(x-sk[i].x));
        p[++sz].l=sk[i].y-dis;  p[sz].r=sk[i].y+dis;
    }
    sort(p+1,p+sz+1,cmp2);
    int i,j;
    for (i=1;i<=sz;i++){
        r=p[i].r;
        for (j=i+1;j<=sz;j++){
            if (p[j].l>r) break;
            r=max(r,p[j].r);
        }
        len+=r-p[i].l; i=j;
    }
    return len;
}
double calc(double l,double fl,double fmid,double fr){return l/6.0*(fl+4.0*fmid+fr);}
double simpson(double l,double mid,double r,double fl,double fmid,double fr,double s)
{
    double m1=(l+mid)/2,m2=(mid+r)/2;
    double f1=getf(m1),f2=getf(m2);
    double g1=calc(mid-l,fl,f1,fmid),g2=calc(r-mid,fmid,f2,fr);
    if (fabs(g1+g2-s)<eps) return g1+g2;
    return simpson(l,m1,mid,fl,f1,fmid,g1)+simpson(mid,m2,r,fmid,f2,fr,g2);
}
void work()
{
    for (int i=1;i<=m;i++) xl[i]=sk[i].x-sk[i].r,xr[i]=sk[i].x+sk[i].r,sk[i].r*=sk[i].r;
    int i,j; double l,r;
    double fl,fr,fmid;
    for (i=1;i<=m;i++){
        l=xl[i]; r=xr[i];
        for (j=i+1;j<=m;j++){
            if (xl[j]>r) break;
            r=max(r,xr[j]);
        }
        st=i; ed=j-1; i=j-1;
        double mid=(l+r)/2;
        fl=getf(l); fmid=getf(mid); fr=getf(r);
        //cout<<fl<<" "<<fr<<" "<<fmid<<endl;
        ans+=simpson(l,mid,r,fl,fmid,fr,calc(r-l,fl,fmid,fr));
    }
}
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++)scanf("%lf%lf%lf",&a[i].x,&a[i].y,&a[i].r);
    sort(a+1,a+n+1,cmp);
    for (int i=1;i<=n-1;i++)
        for (int j=i+1;j<=n;j++)
            if (dis(a[i],a[j])<=a[j].r-a[i].r) {mark[i]=1;break;}
    for (int i=1;i<=n;i++)
     if (!mark[i]) sk[++m]=a[i];
    sort(sk+1,sk+m+1,cmp1);
    work();
    printf("%.3lf\n",ans);
}

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#define N 2003
#define eps 1e-13
using namespace std;
int n,m,top,st,ed;
bool mark[N];
double xl[N],xr[N],ans;
struct data{double x,y,r;}a[N],sk[N]; 
struct line{double l,r;}p[N];
int cmp(data a,data b){return a.r<b.r;}
int cmp1(data a,data b){return a.x-a.r<b.x-b.r;}
int cmp2(line a,line b){return a.l<b.l;}
double pow(double x){return x*x;}
double dis(data a,data b){return sqrt(pow(a.x-b.x)+pow(a.y-b.y));}
double getf(double x)
{
    double r,dis,len=0;
    int sz=0;
    for (int i=st;i<=ed;i++){
        if (xl[i]>=x||xr[i]<=x) continue;
        dis=sqrt(sk[i].r-pow(x-sk[i].x));
        p[++sz].l=sk[i].y-dis;  p[sz].r=sk[i].y+dis;
    }
    sort(p+1,p+sz+1,cmp2);
    int i,j;
    for (i=1;i<=sz;i++){
        r=p[i].r;
        for (j=i+1;j<=sz;j++){
            if (p[j].l>r) break;
            r=max(r,p[j].r);
        }
        len+=r-p[i].l; i=j-1;
    }
    return len;
}
double calc(double l,double fl,double fmid,double fr){return l/6.0*(fl+4.0*fmid+fr);}
double simpson(double l,double mid,double r,double fl,double fmid,double fr,double s)
{
    double m1=(l+mid)/2,m2=(mid+r)/2;
    double f1=getf(m1),f2=getf(m2);
    double g1=calc(mid-l,fl,f1,fmid),g2=calc(r-mid,fmid,f2,fr);
    if (fabs(g1+g2-s)<eps) return g1+g2;
    return simpson(l,m1,mid,fl,f1,fmid,g1)+simpson(mid,m2,r,fmid,f2,fr,g2);
}
void work()
{
    for (int i=1;i<=m;i++) xl[i]=sk[i].x-sk[i].r,xr[i]=sk[i].x+sk[i].r,sk[i].r*=sk[i].r;
    int i,j; double l,r;
    double fl,fr,fmid;
    for (i=1;i<=m;i++){
        l=xl[i]; r=xr[i];
        for (j=i+1;j<=m;j++){
            if (xl[j]>r) break;
            r=max(r,xr[j]);
        }
        st=i; ed=j-1; i=j-1;
        double mid=(l+r)/2;
        fl=getf(l); fmid=getf(mid); fr=getf(r);
        //cout<<fl<<" "<<fr<<" "<<fmid<<endl;
        ans+=simpson(l,mid,r,fl,fmid,fr,calc(r-l,fl,fmid,fr));
    }
}
int main()
{
    scanf("%d",&n);
    for (int i=1;i<=n;i++)scanf("%lf%lf%lf",&a[i].x,&a[i].y,&a[i].r);
    sort(a+1,a+n+1,cmp);
    for (int i=1;i<=n-1;i++)
        for (int j=i+1;j<=n;j++)
            if (dis(a[i],a[j])<=a[j].r-a[i].r) {mark[i]=1;break;}
    for (int i=1;i<=n;i++)
     if (!mark[i]) sk[++m]=a[i];
    sort(sk+1,sk+m+1,cmp1);
    work();
    printf("%.3lf\n",ans);
}