#include <iostream>
#include <cmath>
using namespace std;
int main(){
    double x,y,j,k,a;
    cin>>x>>y>>j>>k;
    a=sqrt((x-j)*(x-j)+(y-k)*(y-k));
    printf("%.4lf\n",a);
    return 0;
}

### Prompt

In Cpp, your task is to solve 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>
using namespace std;
int main(){
    double x,y,j,k,a;
    cin>>x>>y>>j>>k;
    a=sqrt((x-j)*(x-j)+(y-k)*(y-k));
    printf("%.4lf\n",a);
    return 0;
}

```