#include <iostream>
#include <cmath>
#include<stdio.h>
using namespace std;
int main(){

double x1,y1,x2,y2,res;
cin>>x1>>y1>>x2>>y2;

res=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));

printf("%.8f\n",res);

}
### 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 <cmath>
#include<stdio.h>
using namespace std;
int main(){

double x1,y1,x2,y2,res;
cin>>x1>>y1>>x2>>y2;

res=sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));

printf("%.8f\n",res);

}
```