#include <bits/stdc++.h>
#include <cmath>
using namespace std;
int main(void){
	double a,b,c,d,x,y;
	cin>>a>>b>>c>>d;
	x = c-a;
	y = b-d;
	if(x<0)x =x*-1;
	if(y<0)y =y*-1;
	printf("%lf\n",sqrt(x*x+y*y));
	return 0;
}

### Prompt

Construct a Cpp code solution to the problem outlined:

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 <bits/stdc++.h>
#include <cmath>
using namespace std;
int main(void){
	double a,b,c,d,x,y;
	cin>>a>>b>>c>>d;
	x = c-a;
	y = b-d;
	if(x<0)x =x*-1;
	if(y<0)y =y*-1;
	printf("%lf\n",sqrt(x*x+y*y));
	return 0;
}

```