#include<stdio.h>
#include<string.h>
#include <math.h>
int main(void)
{
	double a,s,d,f,g,h,i,j,z;
	scanf("%lf %lf %lf %lf",&a,&s,&d,&f);
	h=s-f;
	g=a-d;
	z=sqrt(h*h+g*g);
	printf("%lf\n",z);
	return 0;
}
### Prompt

Create a solution in cpp for 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<stdio.h>
#include<string.h>
#include <math.h>
int main(void)
{
	double a,s,d,f,g,h,i,j,z;
	scanf("%lf %lf %lf %lf",&a,&s,&d,&f);
	h=s-f;
	g=a-d;
	z=sqrt(h*h+g*g);
	printf("%lf\n",z);
	return 0;
}
```