#include <iostream>
#include <stdio.h>
#include <cmath>
using namespace std;

double a,b,c,d;
int main(){
	cin >> a >> b >> c >> d;
	double e = sqrt((a-c)*(a-c)+(b-d)*(b-d));
	printf("%.6f\n",e);
}

### Prompt

Generate 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;

double a,b,c,d;
int main(){
	cin >> a >> b >> c >> d;
	double e = sqrt((a-c)*(a-c)+(b-d)*(b-d));
	printf("%.6f\n",e);
}

```