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

int main(){
    double a, b, c, d;
    cin>>a >>b >>c >>d;
    printf("%f\n", sqrt(pow(a-c, 2) + pow(b-d, 2)));
    return 0;
}


### Prompt

Create a solution in Cpp for 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<bits/stdc++.h>
using namespace std;

int main(){
    double a, b, c, d;
    cin>>a >>b >>c >>d;
    printf("%f\n", sqrt(pow(a-c, 2) + pow(b-d, 2)));
    return 0;
}


```