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

int main(){

cout<<fixed<<setprecision(12);
double a,b,c,d;
cin>>a>>b>>c>>d;
double X=pow(c-a,2);
double Y=pow(d-b,2);
cout<<sqrt(X+Y)<<endl;


return 0;
}

### Prompt

Develop a solution in cpp to the problem described below:

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(){

cout<<fixed<<setprecision(12);
double a,b,c,d;
cin>>a>>b>>c>>d;
double X=pow(c-a,2);
double Y=pow(d-b,2);
cout<<sqrt(X+Y)<<endl;


return 0;
}

```