BEE 1015.java

import java.io.IOException;
import java.util.Scanner;
import java.lang.Math;

public class Main{
    public static void main(String[] args) throws IOException{
        Scanner input = new Scanner(System.in);
        float x1 = input.nextFloat();
        float y1 = input.nextFloat();
        float x2 = input.nextFloat();
        float y2 = input.nextFloat();
        double distance = Math.sqrt(Math.pow(x2 - x1, 2) + Math.pow(y2 - y1, 2));
        System.out.printf("%.4f\n", distance);
    }
}