#include <iostream>
#include <math.h>

using namespace std;


int main()
{
	int a = 0, b = 0, c = 0, d = 0, x = 0, y = 0;
	float x1 = 0, y1 = 0;


	cout << "Podaj wspolrzedne punktu A "<<endl;
	cin >> a; cin>> b;
	cout << "Podaj wspolrzedne punktu B" << endl;
	cin >> c; cin >> d;

	x = pow(a, 2) + pow(b, 2);
	x1=sqrt(x);

	y = pow(c, 2) + pow(d, 2);
	y1 = sqrt(y);

	if ((x1 - y1) >= 0) {
		cout << (x1 - y1) << endl;
	}
	if ((x1 - y1) < 0) {
		cout << (y1 - x1) << endl;
	}
retur 0;
}