#include <cstdio>

#include <cmath>

#include <algorithm>

using namespace std;

typedef double db;

const int N=;

int n,t,lm=,rm=-,v[N],q[N],x[N],y[N],r[N];

pair<db,db> b[N];

db F(db a) {

    int tt=;

    db re=,ls=-;

    for(int i=;i<=t;i++) if(fabs(a-x[q[i]])<=r[q[i]]) {

        db k=sqrt(r[q[i]]*r[q[i]]-(a-x[q[i]])*(a-x[q[i]]));

        b[++tt].first=y[q[i]]-k,b[tt].second=y[q[i]]+k;

    }

    sort(b+,b++tt);

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

        if(b[i].first>ls) re+=b[i].second-b[i].first,ls=b[i].second;

        else if(b[i].second>ls) re+=b[i].second-ls,ls=b[i].second;

    }

    return re;

}

db asr(db a,db b,db c,db A,db B,db C) {

    db l=F((a+c)/),r=F((c+b)/),aa=(A+C*+B)*(b-a)/,L=(A+*l+C)*(c-a)/,R=(C+*r+B)*(b-c)/;

    if(fabs(L+R-aa)<=1e-) return aa;

    return asr(a,c,(a+c)/,A,C,l)+asr(c,b,(b+c)/,C,B,r);

}

int main() {

    scanf("%d",&n);

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

        scanf("%d%d%d",&x[i],&y[i],&r[i]);

        lm=min(lm,x[i]-r[i]),rm=max(rm,x[i]+r[i]);

    }

    for(int i=;i<=n;i++) if(!v[i])

    for(int j=;j<=n;j++) if(i!=j&&!v[j]) {

        if(sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]))+r[j]<=r[i]) v[j]=;

    }

    for(int i=;i<=n;i++) if(!v[i]) q[++t]=i;

    printf("%.3f",asr(lm,rm,(lm+rm)/2.0,,,F((lm+rm)/2.0)));

    return ;

}