#include <bits/stdc++.h>
using namespace std;

int main(){
	double x1, y1, x2, y2;
	scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
	printf("%.12lf\n", sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2)));
}


### Prompt

Develop a solution in cpp to the problem described below:

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>
using namespace std;

int main(){
	double x1, y1, x2, y2;
	scanf("%lf%lf%lf%lf", &x1, &y1, &x2, &y2);
	printf("%.12lf\n", sqrt((x1-x2)*(x1-x2) + (y1-y2)*(y1-y2)));
}


```