#include<bits/stdc++.h>
using namespace std;
int main(){
  double a,b,c,d;
  cin>>a>>b>>c>>d;
  printf("%.5f\n", sqrt((a-c)*(a-c)+(b-d)*(b-d)));
}

### 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<bits/stdc++.h>
using namespace std;
int main(){
  double a,b,c,d;
  cin>>a>>b>>c>>d;
  printf("%.5f\n", sqrt((a-c)*(a-c)+(b-d)*(b-d)));
}

```