#include<iostream>

 #include<cstdio>

 #include<algorithm>

 #include<cstring>

 #include<cmath>

 using namespace std;

 const double eps=1e-;

 const int INF=1e9;

 const int mxn=;

 int read(){

     int x=,f=;char ch=getchar();

     while(ch<'' || ch>''){if(ch=='-')f=-;ch=getchar();}

     while(ch>='' && ch<=''){x=x*-''+ch;ch=getchar();}

     return x*f;

 }

 //

 struct cir{

     double x,y,r;

     friend bool operator < (const cir a,const cir b){return a.r<b.r;}

 }c[mxn];int cnt=;

 inline double dist(cir a,cir b){return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));}

 //圆

 struct line{

     double l,r;

     friend bool operator <(const line a,const line b){return a.l<b.l;}

 }a[mxn],b[mxn];int lct=;

 double f(double x){

     int i,j;

     lct=;

     for(i=;i<=cnt;i++){//计算直线截得圆弧长度

         if(fabs(c[i].x-x)>=c[i].r)continue;

         double h= sqrt(c[i].r*c[i].r-(c[i].x-x)*(c[i].x-x));

         a[++lct].l=c[i].y-h;

         a[lct].r=c[i].y+h;

     }

     if(!lct)return ;

     double len=,last=-INF;

     sort(a+,a+lct+);

     for(i=;i<=lct;i++){//线段长度并

         if(a[i].l>last){len+=a[i].r-a[i].l;last=a[i].r;}

         else if(a[i].r>last){len+=a[i].r-last;last=a[i].r;}

     }

 //    printf("x:%.3f  len:%.3f\n",x,len);

     return len;

 }

 inline double sim(double l,double r){

     return (f(l)+*f((l+r)/)+f(r))*(r-l)/;

 }

 double solve(double l,double r,double S){

     double mid=(l+r)/;

     double ls=sim(l,mid);

     double rs=sim(mid,r);

     if(fabs(rs+ls-S)<eps)return ls+rs;

     return solve(l,mid,ls)+solve(mid,r,rs);

 }

 int n;

 double ans=;

 bool del[mxn];

 int main(){

     n=read();

     int i,j;

     double L=INF,R=-INF;

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

         c[i].x=read();    c[i].y=read();    c[i].r=read();

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

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

     }

     //

     sort(c+,c+n+);

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

         for(j=i+;j<=n;j++){

 //            printf("%d %.3f %.3f %.3f %.3f\n",j,c[j].x,c[i].r,c[j].r,dist(c[i],c[j]));

             if(c[j].r-c[i].r>=dist(c[i],c[j]))

                 {del[i]=;break;}

         }

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

         if(!del[i])c[++cnt]=c[i];

     //删去被包含的圆

 //    printf("cnt:%d\n",cnt);

     double tmp=-INF;int blct=;

     for(i=;i<=cnt;i++){

         b[++blct].l=c[i].x-c[i].r;

         b[blct].r=c[i].x+c[i].r;

     }

     sort(b+,b+blct+);

 //    printf("lct:%d\n",blct);

 //    int tlct=t;

     for(i=;i<=blct;i++){

 //        printf("%.3f %.3f\n",b[i].l,b[i].r);

 //        printf("tmp:%.3f\n",tmp);

         if(b[i].r<=tmp)continue;

         L=max(tmp,b[i].l);

 //        printf("%d: %.3f %.3f\n",i,L,a[i].r);

         ans+=solve(L,b[i].r,sim(L,b[i].r));

 //        printf("ANS:%.3f\n",ans);

 //        printf("nlct:%d\n",lct);

         tmp=b[i].r;

     }

 //    ans=solve(L,R,f((L+R)/2));

     printf("%.3f\n",ans);

     return ;

 }