#include <iostream>
#include <cmath>

using namespace std;

double dis(double p0x, double p0y, double p1x=0.0, double p1y=0.0)
{
    double r = sqrt(pow(p0x-p1x, 2.0)+pow(p0y-p1y, 2.0));
	return r;
}

double dis(double p0[3], double p1[3])
{
    double r = sqrt(pow(p0[0]-p1[0], 2.0)+pow(p0[1]-p1[1], 2.0)+pow(p0[2]-p1[2], 2.0));
	return r;
}

int main()
{
    double p0[2] = {4, 5}, p1[2]={1, 1};
    double p2[3] = {3, 4, 5}, p3[3] = {0, 0, 0};

    cout << dis(p0[0], p0[1]) << "\t" << dis(p1[0], p1[1]) << "\t"
             << dis(p0[0], p0[1], p1[0], p1[1])  << "\t" << dis(p2, p3) << endl;

    return 0;
}