#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;
int main(){
	double xa,xb,ya,yb;
	scanf("%lf%lf%lf%lf", &xa, &ya, &xb, &yb);
	printf("%lf\n",(double)hypot(xa-xb,ya-yb) );
	return 0;
}

### Prompt

Your challenge is to write a cpp solution to the following problem:

Write a program which calculates the distance between two points P1(x1, y1) and P2(x2, y2).



Input

Four real numbers x1, y1, x2 and y2 are given in a line.

Output

Print the distance in real number. The output should not contain an absolute error greater than 10-4.

Example

Input

0 0 1 1


Output

1.41421356

### Response

```cpp
#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;
int main(){
	double xa,xb,ya,yb;
	scanf("%lf%lf%lf%lf", &xa, &ya, &xb, &yb);
	printf("%lf\n",(double)hypot(xa-xb,ya-yb) );
	return 0;
}

```