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

int main(){
    double x,y,X,Y;
    scanf("%lf %lf %lf %lf",&x,&y,&X,&Y);
    printf("%.7f\n",sqrt(pow(x-X,2)+pow(y-Y,2)));
}

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

int main(){
    double x,y,X,Y;
    scanf("%lf %lf %lf %lf",&x,&y,&X,&Y);
    printf("%.7f\n",sqrt(pow(x-X,2)+pow(y-Y,2)));
}

```