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

int main(){
	double a, b, c, d;
	cin >> a >> b >> c >> d;
	double ans = sqrt((a - c) * (a - c) + (b - d) *(b - d));
	printf("%.10f\n", ans);
	return 0;
}

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

int main(){
	double a, b, c, d;
	cin >> a >> b >> c >> d;
	double ans = sqrt((a - c) * (a - c) + (b - d) *(b - d));
	printf("%.10f\n", ans);
	return 0;
}

```