#include <bits/stdc++.h>
using namespace std;

typedef long double db;
const db step=0.01;

int n;
db x[50],y[50],r[50];

int main(){
	ios_base::sync_with_stdio(false);
	cin >> n;
	for (int i=1;i<=n;i++) cin >> x[i] >> y[i] >> r[i];
	
	db ans=0;
	for (db nowx=-10;nowx<=20;nowx+=step){
		for (db nowy=-10;nowy<=20;nowy+=step){
			bool flag=0;
			for (int i=1;i<=n;i++){
				if ((nowx-x[i])*(nowx-x[i])+(nowy-y[i])*(nowy-y[i])<=r[i]*r[i]){
					flag=1;
					break;
				}
			}
			if (flag) ans+=step*step;
		}
	}
	cout << ans << "\n";
	return 0;
}