#include<iostream>
#include<cstdio>
#include<cmath>
using namespace std;

int main(){
  double x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  
  printf("%lf\n", sqrt(pow(x2-x1, 2)+pow(y2-y1, 2)));
  
  return 0;
}

### Prompt

Please formulate a CPP solution to 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<cstdio>
#include<cmath>
using namespace std;

int main(){
  double x1, y1, x2, y2;
  cin >> x1 >> y1 >> x2 >> y2;
  
  printf("%lf\n", sqrt(pow(x2-x1, 2)+pow(y2-y1, 2)));
  
  return 0;
}

```