#include <iostream>
#include <cmath>

using namespace std;

int main ()
{ 
	// declare variables
	double x1, y1, x2, y2;
	double distance;
	double side1, side2;

    // prompt user for input values
	cout<< " Please input point coordinates" << endl;
	cin>> x1 >> y1 >> x2 >> y2;

	// input is ready; lets compute side1 and side2
	side1 = y2 - y1;
	side2 = x2 - x1;

	// now compute distance
	distance = sqrt (side1*side1 + side2 *side2);

	cout << " The distance between points given is: " << distance;
    cout << endl;

	return 0;
}