#include <iostream>
#include <math.h>
#include <stdio.h>
using namespace std;
int main(void){
    double a,b,c,d,x,y,z;
    cin>>a>>b>>c>>d;
    x=c-a;
    y=d-b;
    z=x*x+y*y;
    printf ("%8f\n",pow(z, 0.5));
}


### Prompt

Construct a CPP code solution to the problem outlined:

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 <math.h>
#include <stdio.h>
using namespace std;
int main(void){
    double a,b,c,d,x,y,z;
    cin>>a>>b>>c>>d;
    x=c-a;
    y=d-b;
    z=x*x+y*y;
    printf ("%8f\n",pow(z, 0.5));
}


```