#include <iostream>
#include <vector>
#include <math.h>
using namespace std;

double Opt (int X1, int R1, int X2, int R2){
    double Xopt;
    if(X1 < X2){
        Xopt = (X1+X2)/2 + (R1 - R2)/2;
    }else if(X1 > X2){
        Xopt = (X1+X2)/2 + (R2 - R1)/2;
    }else if(X1 == X2){
        Xopt = X1;
    }
    return Xopt;   
}


int main(){
    int N, buff;
    cin >> N;

    vector<int> xyz;
    for(int i = 0; i < N; i++){
        cin >> buff;
        xyz.push_back(buff);
        cin >> buff;
        xyz.push_back(buff);
        cin >> buff;
        xyz.push_back(buff);
    }

    double Xopt, Yopt, Ropt;
    Xopt = Opt(xyz[0], xyz[2], xyz[3], xyz[5]);
    Yopt = Opt(xyz[1], xyz[2], xyz[4], xyz[5]);
    Ropt = 0;

    for(int i = 2; i < N; i++){
        Xopt = Opt(xyz[i*3], xyz[i*3+2], Xopt, Ropt);
        Yopt = Opt(xyz[i*3+1], xyz[i*3+2],Yopt, Ropt);
    }

    double Xd, Yd;

    
    if(Xopt > xyz[(N-1)*3]){
        Xd = (Xopt - xyz[(N-1)*3] - xyz[(N-1)*3+2]);
    }else if(Xopt < xyz[(N-1)*3]){
        Xd = (Xopt - xyz[(N-1)*3] + xyz[(N-1)*3+2]);
    }else if(Xopt == xyz[(N-1)*3]){
        Xd = 0;
    }

    if(Yopt > xyz[(N-1)*3+1]){
        Yd = (Yopt - xyz[(N-1)*3+1] - xyz[(N-1)*3+2]);
    }else if(Yopt < xyz[(N-1)*3+1]){
        Yd = (Yopt - xyz[(N-1)*3+1] + xyz[(N-1)*3+2]);
    }else if(Yopt == xyz[(N-1)*3+1]){
        Yd = 0;
    }
    
    double Distance = sqrt(pow(Xd, 2) + pow(Yd, 2));

    cout << Distance << endl;

    // for(auto n:xyz) cout << n;
}