#include "bits/stdc++.h"
using namespace std;
int main(){
    double a,b,c,d,r;
    cin >> a >> b >> c >> d;
    r = (a-c)*(a-c)+(b-d)*(b-d);
    printf("%.4lf\n",sqrt(r));
    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(){
    double a,b,c,d,r;
    cin >> a >> b >> c >> d;
    r = (a-c)*(a-c)+(b-d)*(b-d);
    printf("%.4lf\n",sqrt(r));
    return 0;
}

```