#include<stdio.h>
#include<math.h>

int main(){
	double a,b,c,d;
	scanf("%lf %lf %lf %lf",&a,&b,&c,&d);
	printf("%.8lf\n",sqrt(pow(c-a,2.0)+pow((d-b),2.0)));
}
### Prompt

Please create a solution in cpp 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<stdio.h>
#include<math.h>

int main(){
	double a,b,c,d;
	scanf("%lf %lf %lf %lf",&a,&b,&c,&d);
	printf("%.8lf\n",sqrt(pow(c-a,2.0)+pow((d-b),2.0)));
}
```